<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2026 Workiva-->
<!--r:2a783a54-3af8-4517-b695-92190b63f92c,g:2339dc14-182d-400f-b587-4ceb18b6867c-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member"/>
  <link:roleRef roleURI="http://www.boozallen.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFSTOCKHOLDERSEQUITY" xlink:type="simple" xlink:href="bah-20251231.xsd#CONDENSEDCONSOLIDATEDSTATEMENTSOFSTOCKHOLDERSEQUITY"/>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFSTOCKHOLDERSEQUITY" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_9daef690-554b-4c0e-a6d1-c7f42de4dcce" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_a8a870ff-4c17-4d2e-bd78-5c7b97bef646" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_9daef690-554b-4c0e-a6d1-c7f42de4dcce" xlink:to="loc_us-gaap_StatementTable_a8a870ff-4c17-4d2e-bd78-5c7b97bef646" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_4e494d8d-9f79-4b0b-8010-85acc7bed419" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_a8a870ff-4c17-4d2e-bd78-5c7b97bef646" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_4e494d8d-9f79-4b0b-8010-85acc7bed419" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_4e494d8d-9f79-4b0b-8010-85acc7bed419_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_4e494d8d-9f79-4b0b-8010-85acc7bed419" xlink:to="loc_us-gaap_EquityComponentDomain_4e494d8d-9f79-4b0b-8010-85acc7bed419_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_54887c6f-deff-4848-8f38-f3c5aac910df" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_4e494d8d-9f79-4b0b-8010-85acc7bed419" xlink:to="loc_us-gaap_EquityComponentDomain_54887c6f-deff-4848-8f38-f3c5aac910df" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_c811d691-5e49-4e0b-9458-b7f42ca6d3f4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_54887c6f-deff-4848-8f38-f3c5aac910df" xlink:to="loc_us-gaap_CommonStockMember_c811d691-5e49-4e0b-9458-b7f42ca6d3f4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonMember_d09b054a-95ee-4f85-a681-fff825be990e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TreasuryStockCommonMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_54887c6f-deff-4848-8f38-f3c5aac910df" xlink:to="loc_us-gaap_TreasuryStockCommonMember_d09b054a-95ee-4f85-a681-fff825be990e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_00502b8b-4990-401b-a371-3dcc2df9ec6c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_54887c6f-deff-4848-8f38-f3c5aac910df" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_00502b8b-4990-401b-a371-3dcc2df9ec6c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_0ae05416-cab4-4c52-b0e0-7e3c0fea1e2c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_54887c6f-deff-4848-8f38-f3c5aac910df" xlink:to="loc_us-gaap_RetainedEarningsMember_0ae05416-cab4-4c52-b0e0-7e3c0fea1e2c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_4a18ceef-43f3-46a5-a72f-3070bc57f362" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_54887c6f-deff-4848-8f38-f3c5aac910df" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_4a18ceef-43f3-46a5-a72f-3070bc57f362" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_0e288f53-8ee9-4149-8269-a7a6a41e0fb1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_a8a870ff-4c17-4d2e-bd78-5c7b97bef646" xlink:to="loc_us-gaap_StatementClassOfStockAxis_0e288f53-8ee9-4149-8269-a7a6a41e0fb1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_0e288f53-8ee9-4149-8269-a7a6a41e0fb1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_0e288f53-8ee9-4149-8269-a7a6a41e0fb1" xlink:to="loc_us-gaap_ClassOfStockDomain_0e288f53-8ee9-4149-8269-a7a6a41e0fb1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_6a124976-7950-4198-ae16-3d37e537db3c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_0e288f53-8ee9-4149-8269-a7a6a41e0fb1" xlink:to="loc_us-gaap_ClassOfStockDomain_6a124976-7950-4198-ae16-3d37e537db3c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_63944d10-3ce0-42b8-b028-78853e480edd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_6a124976-7950-4198-ae16-3d37e537db3c" xlink:to="loc_us-gaap_CommonClassAMember_63944d10-3ce0-42b8-b028-78853e480edd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_51c04a80-a54e-4be5-9485-74b67ebccc99" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_9daef690-554b-4c0e-a6d1-c7f42de4dcce" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_51c04a80-a54e-4be5-9485-74b67ebccc99" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_6298e2c2-9996-4d40-8fb1-1ad6818d54d6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_51c04a80-a54e-4be5-9485-74b67ebccc99" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_6298e2c2-9996-4d40-8fb1-1ad6818d54d6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_e8965ff1-8095-4253-bd74-5e55ae642657" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_51c04a80-a54e-4be5-9485-74b67ebccc99" xlink:to="loc_us-gaap_StockholdersEquity_e8965ff1-8095-4253-bd74-5e55ae642657" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonShares_5b13ee04-19db-4842-8a63-6fe5b902bfd3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TreasuryStockCommonShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_51c04a80-a54e-4be5-9485-74b67ebccc99" xlink:to="loc_us-gaap_TreasuryStockCommonShares_5b13ee04-19db-4842-8a63-6fe5b902bfd3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_afaf672b-aef3-4ec7-8a9c-7f37b6063111" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_51c04a80-a54e-4be5-9485-74b67ebccc99" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_afaf672b-aef3-4ec7-8a9c-7f37b6063111" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_d6dd03b2-8bbf-4864-a9fe-51a24c9da97a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodValueNewIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_51c04a80-a54e-4be5-9485-74b67ebccc99" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_d6dd03b2-8bbf-4864-a9fe-51a24c9da97a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_35ef1090-bdf0-4343-8799-3dacbc87871f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_51c04a80-a54e-4be5-9485-74b67ebccc99" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_35ef1090-bdf0-4343-8799-3dacbc87871f" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_7a563f74-4c71-4714-98c0-91f68d37ef68" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_51c04a80-a54e-4be5-9485-74b67ebccc99" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_7a563f74-4c71-4714-98c0-91f68d37ef68" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockSharesAcquired_cfa6bd30-8112-47a1-8471-ff7865e7f05d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TreasuryStockSharesAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_51c04a80-a54e-4be5-9485-74b67ebccc99" xlink:to="loc_us-gaap_TreasuryStockSharesAcquired_cfa6bd30-8112-47a1-8471-ff7865e7f05d" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_d663e88f-ca30-4825-a383-8c1c0e1ece32" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TreasuryStockValueAcquiredCostMethod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_51c04a80-a54e-4be5-9485-74b67ebccc99" xlink:to="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_d663e88f-ca30-4825-a383-8c1c0e1ece32" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_ea0c4139-1a4a-464d-b374-a993ec656a53" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_51c04a80-a54e-4be5-9485-74b67ebccc99" xlink:to="loc_us-gaap_NetIncomeLoss_ea0c4139-1a4a-464d-b374-a993ec656a53" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_2c321d09-4973-4dba-a5f6-aae1ac4b67ba" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_51c04a80-a54e-4be5-9485-74b67ebccc99" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_2c321d09-4973-4dba-a5f6-aae1ac4b67ba" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsCommonStockCash_8a4bb99d-7706-45b7-b13e-268008589693" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DividendsCommonStockCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_51c04a80-a54e-4be5-9485-74b67ebccc99" xlink:to="loc_us-gaap_DividendsCommonStockCash_8a4bb99d-7706-45b7-b13e-268008589693" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_ed227100-889b-4606-98ee-c5765e5fe284" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_51c04a80-a54e-4be5-9485-74b67ebccc99" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_ed227100-889b-4606-98ee-c5765e5fe284" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_ae7c517e-ef3d-47ff-a938-e158b90e6467" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_dcdb27b9-6764-4292-9544-40b9fb822f68" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquity"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonShares_fa4f14d8-1a74-4307-8c71-2c5f71f077f8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TreasuryStockCommonShares"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.boozallen.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFSTOCKHOLDERSEQUITYParenthetical" xlink:type="simple" xlink:href="bah-20251231.xsd#CONDENSEDCONSOLIDATEDSTATEMENTSOFSTOCKHOLDERSEQUITYParenthetical"/>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFSTOCKHOLDERSEQUITYParenthetical" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_6d943323-c662-4396-b7bf-1f865ab00952" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_c430d88b-08ac-4972-a5cb-a9a27166ab97" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_6d943323-c662-4396-b7bf-1f865ab00952" xlink:to="loc_us-gaap_StatementTable_c430d88b-08ac-4972-a5cb-a9a27166ab97" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_e1f38864-7b94-42dd-a603-1b6246937ca9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_c430d88b-08ac-4972-a5cb-a9a27166ab97" xlink:to="loc_us-gaap_StatementClassOfStockAxis_e1f38864-7b94-42dd-a603-1b6246937ca9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_e1f38864-7b94-42dd-a603-1b6246937ca9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_e1f38864-7b94-42dd-a603-1b6246937ca9" xlink:to="loc_us-gaap_ClassOfStockDomain_e1f38864-7b94-42dd-a603-1b6246937ca9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_e5e234ef-89a2-45b6-a371-9ef33aa76601" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_e1f38864-7b94-42dd-a603-1b6246937ca9" xlink:to="loc_us-gaap_ClassOfStockDomain_e5e234ef-89a2-45b6-a371-9ef33aa76601" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_a3beac72-764e-45cf-8308-48bb5913ae1d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_e5e234ef-89a2-45b6-a371-9ef33aa76601" xlink:to="loc_us-gaap_CommonClassAMember_a3beac72-764e-45cf-8308-48bb5913ae1d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockSharesAcquired_99c88f26-add4-4407-90cc-18395e5bb635" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TreasuryStockSharesAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_6d943323-c662-4396-b7bf-1f865ab00952" xlink:to="loc_us-gaap_TreasuryStockSharesAcquired_99c88f26-add4-4407-90cc-18395e5bb635" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_64d15107-61f1-430d-a2df-61cdebf243de" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TreasuryStockValueAcquiredCostMethod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_6d943323-c662-4396-b7bf-1f865ab00952" xlink:to="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_64d15107-61f1-430d-a2df-61cdebf243de" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_RepurchaseOfStockToSatisfyTaxWithholdingsRestrictedStockAmount_fb2e6ba0-5492-4f1a-b270-5276e55994f9" xlink:href="bah-20251231.xsd#bah_RepurchaseOfStockToSatisfyTaxWithholdingsRestrictedStockAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_6d943323-c662-4396-b7bf-1f865ab00952" xlink:to="loc_bah_RepurchaseOfStockToSatisfyTaxWithholdingsRestrictedStockAmount_fb2e6ba0-5492-4f1a-b270-5276e55994f9" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.boozallen.com/role/RevenueScheduleofDisaggregationofRevenueDetails" xlink:type="simple" xlink:href="bah-20251231.xsd#RevenueScheduleofDisaggregationofRevenueDetails"/>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/RevenueScheduleofDisaggregationofRevenueDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_967ececb-f1d9-47ae-b122-98b7ee04efef" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_f427377a-212c-49ec-bb3b-4d7c06ac0f7b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_967ececb-f1d9-47ae-b122-98b7ee04efef" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_f427377a-212c-49ec-bb3b-4d7c06ac0f7b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerBasisOfPricingAxis_87879e58-5699-446f-aa3d-41e37026d319" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ContractWithCustomerBasisOfPricingAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_f427377a-212c-49ec-bb3b-4d7c06ac0f7b" xlink:to="loc_us-gaap_ContractWithCustomerBasisOfPricingAxis_87879e58-5699-446f-aa3d-41e37026d319" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_87879e58-5699-446f-aa3d-41e37026d319_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ContractWithCustomerBasisOfPricingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ContractWithCustomerBasisOfPricingAxis_87879e58-5699-446f-aa3d-41e37026d319" xlink:to="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_87879e58-5699-446f-aa3d-41e37026d319_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_ef341385-6a0b-4a56-8d93-88cad28d4f5c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ContractWithCustomerBasisOfPricingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ContractWithCustomerBasisOfPricingAxis_87879e58-5699-446f-aa3d-41e37026d319" xlink:to="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_ef341385-6a0b-4a56-8d93-88cad28d4f5c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_CostReimbursableContractMember_e027acbc-11d5-4f84-9d0e-a6c991f9cddd" xlink:href="bah-20251231.xsd#bah_CostReimbursableContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_ef341385-6a0b-4a56-8d93-88cad28d4f5c" xlink:to="loc_bah_CostReimbursableContractMember_e027acbc-11d5-4f84-9d0e-a6c991f9cddd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TimeAndMaterialsContractMember_556e41a5-7a9c-46ea-a2ba-4ac6fad8224b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TimeAndMaterialsContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_ef341385-6a0b-4a56-8d93-88cad28d4f5c" xlink:to="loc_us-gaap_TimeAndMaterialsContractMember_556e41a5-7a9c-46ea-a2ba-4ac6fad8224b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FixedPriceContractMember_056bfd30-4557-4ed9-912c-3c156aeab4fc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FixedPriceContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_ef341385-6a0b-4a56-8d93-88cad28d4f5c" xlink:to="loc_us-gaap_FixedPriceContractMember_056bfd30-4557-4ed9-912c-3c156aeab4fc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MajorCustomersAxis_781e3474-d753-4bd6-8846-02f5faa7169b" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MajorCustomersAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_f427377a-212c-49ec-bb3b-4d7c06ac0f7b" xlink:to="loc_srt_MajorCustomersAxis_781e3474-d753-4bd6-8846-02f5faa7169b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_781e3474-d753-4bd6-8846-02f5faa7169b_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_MajorCustomersAxis_781e3474-d753-4bd6-8846-02f5faa7169b" xlink:to="loc_srt_NameOfMajorCustomerDomain_781e3474-d753-4bd6-8846-02f5faa7169b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_9665553c-19e3-49a2-b0ca-9f9f3e168110" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_MajorCustomersAxis_781e3474-d753-4bd6-8846-02f5faa7169b" xlink:to="loc_srt_NameOfMajorCustomerDomain_9665553c-19e3-49a2-b0ca-9f9f3e168110" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_DefenseClientsMember_178bd29d-aefc-4b16-9794-48d89df91aa4" xlink:href="bah-20251231.xsd#bah_DefenseClientsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_9665553c-19e3-49a2-b0ca-9f9f3e168110" xlink:to="loc_bah_DefenseClientsMember_178bd29d-aefc-4b16-9794-48d89df91aa4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_IntelligenceClientsMember_2203a7dc-e19a-4476-902d-cb73cd1749aa" xlink:href="bah-20251231.xsd#bah_IntelligenceClientsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_9665553c-19e3-49a2-b0ca-9f9f3e168110" xlink:to="loc_bah_IntelligenceClientsMember_2203a7dc-e19a-4476-902d-cb73cd1749aa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_CivilClientsMember_eed9c083-20b7-4a70-83fb-adecb622e09d" xlink:href="bah-20251231.xsd#bah_CivilClientsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_9665553c-19e3-49a2-b0ca-9f9f3e168110" xlink:to="loc_bah_CivilClientsMember_eed9c083-20b7-4a70-83fb-adecb622e09d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerSalesChannelAxis_edea707c-37c7-4a3a-8ac1-f47726fe73b6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ContractWithCustomerSalesChannelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_f427377a-212c-49ec-bb3b-4d7c06ac0f7b" xlink:to="loc_us-gaap_ContractWithCustomerSalesChannelAxis_edea707c-37c7-4a3a-8ac1-f47726fe73b6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerSalesChannelDomain_edea707c-37c7-4a3a-8ac1-f47726fe73b6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ContractWithCustomerSalesChannelDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelAxis_edea707c-37c7-4a3a-8ac1-f47726fe73b6" xlink:to="loc_us-gaap_ContractWithCustomerSalesChannelDomain_edea707c-37c7-4a3a-8ac1-f47726fe73b6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerSalesChannelDomain_645a821d-9f11-4dda-832d-8fc7a0b0ec11" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ContractWithCustomerSalesChannelDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelAxis_edea707c-37c7-4a3a-8ac1-f47726fe73b6" xlink:to="loc_us-gaap_ContractWithCustomerSalesChannelDomain_645a821d-9f11-4dda-832d-8fc7a0b0ec11" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SalesChannelDirectlyToConsumerMember_40201414-67ce-4225-b7f6-09983e83f8ac" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SalesChannelDirectlyToConsumerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelDomain_645a821d-9f11-4dda-832d-8fc7a0b0ec11" xlink:to="loc_us-gaap_SalesChannelDirectlyToConsumerMember_40201414-67ce-4225-b7f6-09983e83f8ac" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SalesChannelThroughIntermediaryMember_750e361d-d478-4437-9181-178537cd6be2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SalesChannelThroughIntermediaryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelDomain_645a821d-9f11-4dda-832d-8fc7a0b0ec11" xlink:to="loc_us-gaap_SalesChannelThroughIntermediaryMember_750e361d-d478-4437-9181-178537cd6be2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_6e3bdb81-bf66-4b76-9b95-b36898a403d5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_f427377a-212c-49ec-bb3b-4d7c06ac0f7b" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_6e3bdb81-bf66-4b76-9b95-b36898a403d5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_6e3bdb81-bf66-4b76-9b95-b36898a403d5_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_6e3bdb81-bf66-4b76-9b95-b36898a403d5" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_6e3bdb81-bf66-4b76-9b95-b36898a403d5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_2fe98fd3-931a-4b3c-b2bd-f630f3ab2af4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_6e3bdb81-bf66-4b76-9b95-b36898a403d5" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_2fe98fd3-931a-4b3c-b2bd-f630f3ab2af4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerMember_ef0de89d-03dc-45dd-8305-22339f37378b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueFromContractWithCustomerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_2fe98fd3-931a-4b3c-b2bd-f630f3ab2af4" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerMember_ef0de89d-03dc-45dd-8305-22339f37378b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_4a22330e-8dac-4f25-8831-b0350ffe833a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_f427377a-212c-49ec-bb3b-4d7c06ac0f7b" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_4a22330e-8dac-4f25-8831-b0350ffe833a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_4a22330e-8dac-4f25-8831-b0350ffe833a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_4a22330e-8dac-4f25-8831-b0350ffe833a" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_4a22330e-8dac-4f25-8831-b0350ffe833a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_37943c14-15d4-4bdb-85bc-f86706a4e1ff" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_4a22330e-8dac-4f25-8831-b0350ffe833a" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_37943c14-15d4-4bdb-85bc-f86706a4e1ff" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProductConcentrationRiskMember_040409fa-4f16-4fca-8412-ccdfb52e9065" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProductConcentrationRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_37943c14-15d4-4bdb-85bc-f86706a4e1ff" xlink:to="loc_us-gaap_ProductConcentrationRiskMember_040409fa-4f16-4fca-8412-ccdfb52e9065" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerConcentrationRiskMember_b8f81a17-643a-476c-a8f6-3e94ac155016" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CustomerConcentrationRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_37943c14-15d4-4bdb-85bc-f86706a4e1ff" xlink:to="loc_us-gaap_CustomerConcentrationRiskMember_b8f81a17-643a-476c-a8f6-3e94ac155016" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_ContractorConcentrationTypeRiskMember_8505371e-3afa-4cdf-aed0-4f81645dca0a" xlink:href="bah-20251231.xsd#bah_ContractorConcentrationTypeRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_37943c14-15d4-4bdb-85bc-f86706a4e1ff" xlink:to="loc_bah_ContractorConcentrationTypeRiskMember_8505371e-3afa-4cdf-aed0-4f81645dca0a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_fe18a4ab-73f6-4aa8-a1f9-55b54e45033d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_967ececb-f1d9-47ae-b122-98b7ee04efef" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_fe18a4ab-73f6-4aa8-a1f9-55b54e45033d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_14bbdb94-6460-4697-bf2f-fe0d88622243" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskPercentage1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_967ececb-f1d9-47ae-b122-98b7ee04efef" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_14bbdb94-6460-4697-bf2f-fe0d88622243" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.boozallen.com/role/RevenueNarrativeDetails" xlink:type="simple" xlink:href="bah-20251231.xsd#RevenueNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/RevenueNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_4c9b3d18-57c5-489d-bcdc-851eedba84d0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_0f664ee7-2231-4552-8c17-252d87de9478" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_4c9b3d18-57c5-489d-bcdc-851eedba84d0" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_0f664ee7-2231-4552-8c17-252d87de9478" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_c1daf4e7-25a9-4ecc-8b5a-94367f5b8c0e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_0f664ee7-2231-4552-8c17-252d87de9478" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_c1daf4e7-25a9-4ecc-8b5a-94367f5b8c0e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationPercentage_f82e57a2-ba0a-4bfe-a263-1af18d33dd3e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligationPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_4c9b3d18-57c5-489d-bcdc-851eedba84d0" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationPercentage_f82e57a2-ba0a-4bfe-a263-1af18d33dd3e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_5e7be395-a948-43c8-a5ad-a2cdb99a8d84" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_4c9b3d18-57c5-489d-bcdc-851eedba84d0" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_5e7be395-a948-43c8-a5ad-a2cdb99a8d84" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.boozallen.com/role/RevenueNarrativeDetails_1" xlink:type="simple" xlink:href="bah-20251231.xsd#RevenueNarrativeDetails_1"/>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/RevenueNarrativeDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_4c9b3d18-57c5-489d-bcdc-851eedba84d0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_0f664ee7-2231-4552-8c17-252d87de9478" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_4c9b3d18-57c5-489d-bcdc-851eedba84d0" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_0f664ee7-2231-4552-8c17-252d87de9478" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationPercentage_f82e57a2-ba0a-4bfe-a263-1af18d33dd3e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligationPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_4c9b3d18-57c5-489d-bcdc-851eedba84d0" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationPercentage_f82e57a2-ba0a-4bfe-a263-1af18d33dd3e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_5e7be395-a948-43c8-a5ad-a2cdb99a8d84" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_4c9b3d18-57c5-489d-bcdc-851eedba84d0" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_5e7be395-a948-43c8-a5ad-a2cdb99a8d84" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.boozallen.com/role/EarningsPerShareDetails" xlink:type="simple" xlink:href="bah-20251231.xsd#EarningsPerShareDetails"/>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/EarningsPerShareDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_bah_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassLineItems_c9cc862b-c55f-40e7-9f9b-8b9e6562a363" xlink:href="bah-20251231.xsd#bah_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassTable_cbc68c76-41d3-412e-95bb-4005ac0854a4" xlink:href="bah-20251231.xsd#bah_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_bah_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassLineItems_c9cc862b-c55f-40e7-9f9b-8b9e6562a363" xlink:to="loc_bah_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassTable_cbc68c76-41d3-412e-95bb-4005ac0854a4" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_958549d4-f63e-4ed7-8ff4-a548225c4f53" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_bah_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassTable_cbc68c76-41d3-412e-95bb-4005ac0854a4" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_958549d4-f63e-4ed7-8ff4-a548225c4f53" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_958549d4-f63e-4ed7-8ff4-a548225c4f53_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_958549d4-f63e-4ed7-8ff4-a548225c4f53" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_958549d4-f63e-4ed7-8ff4-a548225c4f53_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_100da3a2-ad4a-4a7d-8a2e-8ee59f073c26" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_958549d4-f63e-4ed7-8ff4-a548225c4f53" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_100da3a2-ad4a-4a7d-8a2e-8ee59f073c26" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockMember_7bedc70e-2256-40d0-98ae-c2352a8d8b8b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestrictedStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_100da3a2-ad4a-4a7d-8a2e-8ee59f073c26" xlink:to="loc_us-gaap_RestrictedStockMember_7bedc70e-2256-40d0-98ae-c2352a8d8b8b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UndistributedEarnings_8a0d0676-7626-4501-809f-67b99a91ebe3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UndistributedEarnings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bah_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassLineItems_c9cc862b-c55f-40e7-9f9b-8b9e6562a363" xlink:to="loc_us-gaap_UndistributedEarnings_8a0d0676-7626-4501-809f-67b99a91ebe3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UndistributedEarningsDiluted_bf740c4b-cd85-4560-b81e-39cd362a3371" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UndistributedEarningsDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bah_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassLineItems_c9cc862b-c55f-40e7-9f9b-8b9e6562a363" xlink:to="loc_us-gaap_UndistributedEarningsDiluted_bf740c4b-cd85-4560-b81e-39cd362a3371" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_0a7acdf6-6206-4562-90d3-b8a29d0b0d70" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bah_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassLineItems_c9cc862b-c55f-40e7-9f9b-8b9e6562a363" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_0a7acdf6-6206-4562-90d3-b8a29d0b0d70" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment_f4f66355-f845-45d0-99ec-f44aa6c86d24" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bah_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassLineItems_c9cc862b-c55f-40e7-9f9b-8b9e6562a363" xlink:to="loc_us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment_f4f66355-f845-45d0-99ec-f44aa6c86d24" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_95cde95e-8752-48cf-8276-4eb10a2a91f5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bah_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassLineItems_c9cc862b-c55f-40e7-9f9b-8b9e6562a363" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_95cde95e-8752-48cf-8276-4eb10a2a91f5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareReconciliationAbstract_a20f66ae-e834-4334-8ef2-fb2c203a4c34" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EarningsPerShareReconciliationAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bah_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassLineItems_c9cc862b-c55f-40e7-9f9b-8b9e6562a363" xlink:to="loc_us-gaap_EarningsPerShareReconciliationAbstract_a20f66ae-e834-4334-8ef2-fb2c203a4c34" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasic_70f212c5-1043-403a-aa20-cf64dac0f2cc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EarningsPerShareBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareReconciliationAbstract_a20f66ae-e834-4334-8ef2-fb2c203a4c34" xlink:to="loc_us-gaap_EarningsPerShareBasic_70f212c5-1043-403a-aa20-cf64dac0f2cc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDiluted_070758fd-dff7-4a5c-8dee-54e25b245f36" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EarningsPerShareDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareReconciliationAbstract_a20f66ae-e834-4334-8ef2-fb2c203a4c34" xlink:to="loc_us-gaap_EarningsPerShareDiluted_070758fd-dff7-4a5c-8dee-54e25b245f36" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncrementalCommonSharesAttributableToParticipatingNonvestedSharesWithNonForfeitableDividendRights_cde0ec50-3b15-4f94-8c24-8fb0d5e544c9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncrementalCommonSharesAttributableToParticipatingNonvestedSharesWithNonForfeitableDividendRights"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bah_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassLineItems_c9cc862b-c55f-40e7-9f9b-8b9e6562a363" xlink:to="loc_us-gaap_IncrementalCommonSharesAttributableToParticipatingNonvestedSharesWithNonForfeitableDividendRights_cde0ec50-3b15-4f94-8c24-8fb0d5e544c9" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.boozallen.com/role/IntangibleAssetsDetails" xlink:type="simple" xlink:href="bah-20251231.xsd#IntangibleAssetsDetails"/>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/IntangibleAssetsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_813b1e64-5482-49af-bb77-f3f575f5d960" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_344bd1cb-51c5-4c53-96bd-be853df03a78" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_813b1e64-5482-49af-bb77-f3f575f5d960" xlink:to="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_344bd1cb-51c5-4c53-96bd-be853df03a78" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_be71d3f3-758b-423d-bd10-0c03d09b9e06" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_344bd1cb-51c5-4c53-96bd-be853df03a78" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_be71d3f3-758b-423d-bd10-0c03d09b9e06" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_be71d3f3-758b-423d-bd10-0c03d09b9e06_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_be71d3f3-758b-423d-bd10-0c03d09b9e06" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_be71d3f3-758b-423d-bd10-0c03d09b9e06_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_19163246-8aeb-404b-a45f-3208227f1236" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_be71d3f3-758b-423d-bd10-0c03d09b9e06" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_19163246-8aeb-404b-a45f-3208227f1236" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_CustomerContractsAndRelatedCustomerRelationshipsMember_1bd381be-7a3f-45fd-81c4-04254fdcc5fe" xlink:href="bah-20251231.xsd#bah_CustomerContractsAndRelatedCustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_19163246-8aeb-404b-a45f-3208227f1236" xlink:to="loc_bah_CustomerContractsAndRelatedCustomerRelationshipsMember_1bd381be-7a3f-45fd-81c4-04254fdcc5fe" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComputerSoftwareIntangibleAssetMember_7767837a-d542-4fa3-b034-4dfe46d46e8d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ComputerSoftwareIntangibleAssetMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_19163246-8aeb-404b-a45f-3208227f1236" xlink:to="loc_us-gaap_ComputerSoftwareIntangibleAssetMember_7767837a-d542-4fa3-b034-4dfe46d46e8d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_0eda68eb-c6e5-49fc-afef-4b1fd7fc26a9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_344bd1cb-51c5-4c53-96bd-be853df03a78" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_0eda68eb-c6e5-49fc-afef-4b1fd7fc26a9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_0eda68eb-c6e5-49fc-afef-4b1fd7fc26a9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_0eda68eb-c6e5-49fc-afef-4b1fd7fc26a9" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_0eda68eb-c6e5-49fc-afef-4b1fd7fc26a9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_b1a93e7e-9e83-4ae9-9e78-0060a9833444" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_0eda68eb-c6e5-49fc-afef-4b1fd7fc26a9" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_b1a93e7e-9e83-4ae9-9e78-0060a9833444" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TradeNamesMember_10396d77-ea8b-4844-a59b-5051dcb795ca" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TradeNamesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_b1a93e7e-9e83-4ae9-9e78-0060a9833444" xlink:to="loc_us-gaap_TradeNamesMember_10396d77-ea8b-4844-a59b-5051dcb795ca" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNetAbstract_7f80b780-fcc9-4709-b77a-0205f1141706" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsNetAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_813b1e64-5482-49af-bb77-f3f575f5d960" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsNetAbstract_7f80b780-fcc9-4709-b77a-0205f1141706" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_f25a9de8-9f6a-43d7-b017-9a9866e3c423" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsNetAbstract_7f80b780-fcc9-4709-b77a-0205f1141706" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_f25a9de8-9f6a-43d7-b017-9a9866e3c423" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_8fcec31b-1d0f-403e-bad3-737751c7ea8f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsNetAbstract_7f80b780-fcc9-4709-b77a-0205f1141706" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_8fcec31b-1d0f-403e-bad3-737751c7ea8f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_88fc3b84-89f1-4f1a-828f-ffb79ffdd303" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsNetAbstract_7f80b780-fcc9-4709-b77a-0205f1141706" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsNet_88fc3b84-89f1-4f1a-828f-ffb79ffdd303" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwillAbstract_f3b7771a-90d9-4155-91c4-ff8c9fba9f7b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwillAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_813b1e64-5482-49af-bb77-f3f575f5d960" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwillAbstract_f3b7771a-90d9-4155-91c4-ff8c9fba9f7b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill_a00c6eee-27d6-40b8-9bdd-3a13f9fc2076" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwillAbstract_f3b7771a-90d9-4155-91c4-ff8c9fba9f7b" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill_a00c6eee-27d6-40b8-9bdd-3a13f9fc2076" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntangibleAssetsGrossExcludingGoodwill_565dfdd5-c46e-455c-bca0-e11e54f68d65" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IntangibleAssetsGrossExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_813b1e64-5482-49af-bb77-f3f575f5d960" xlink:to="loc_us-gaap_IntangibleAssetsGrossExcludingGoodwill_565dfdd5-c46e-455c-bca0-e11e54f68d65" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_301ee145-b7a1-43ce-8bcd-11611a481598" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_813b1e64-5482-49af-bb77-f3f575f5d960" xlink:to="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_301ee145-b7a1-43ce-8bcd-11611a481598" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.boozallen.com/role/DebtScheduleofDebtDetails" xlink:type="simple" xlink:href="bah-20251231.xsd#DebtScheduleofDebtDetails"/>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/DebtScheduleofDebtDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_24aaf602-f7b7-42d3-88a8-ced43a28fbf8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_84d54404-2726-4c36-8f15-0f83e54d5ee8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_24aaf602-f7b7-42d3-88a8-ced43a28fbf8" xlink:to="loc_us-gaap_DebtInstrumentTable_84d54404-2726-4c36-8f15-0f83e54d5ee8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_43cdd5ca-9333-47f4-9fc3-2bdebf739c73" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_84d54404-2726-4c36-8f15-0f83e54d5ee8" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_43cdd5ca-9333-47f4-9fc3-2bdebf739c73" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_43cdd5ca-9333-47f4-9fc3-2bdebf739c73_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_43cdd5ca-9333-47f4-9fc3-2bdebf739c73" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_43cdd5ca-9333-47f4-9fc3-2bdebf739c73_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_34a0c206-cc36-45b9-8088-7b4690db9d2a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_43cdd5ca-9333-47f4-9fc3-2bdebf739c73" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_34a0c206-cc36-45b9-8088-7b4690db9d2a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebtMember_876d5768-abb7-4575-8a63-9acd3fcf7158" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_34a0c206-cc36-45b9-8088-7b4690db9d2a" xlink:to="loc_us-gaap_SecuredDebtMember_876d5768-abb7-4575-8a63-9acd3fcf7158" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_721491e4-86a2-4994-8def-c94275dbd7f9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_34a0c206-cc36-45b9-8088-7b4690db9d2a" xlink:to="loc_us-gaap_SeniorNotesMember_721491e4-86a2-4994-8def-c94275dbd7f9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_5a83b2b5-26c3-4d08-8a0d-0edae99c979f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_84d54404-2726-4c36-8f15-0f83e54d5ee8" xlink:to="loc_us-gaap_DebtInstrumentAxis_5a83b2b5-26c3-4d08-8a0d-0edae99c979f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_5a83b2b5-26c3-4d08-8a0d-0edae99c979f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_5a83b2b5-26c3-4d08-8a0d-0edae99c979f" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_5a83b2b5-26c3-4d08-8a0d-0edae99c979f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_6e245a4c-84d3-4b7a-9261-1de6e6820b17" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_5a83b2b5-26c3-4d08-8a0d-0edae99c979f" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_6e245a4c-84d3-4b7a-9261-1de6e6820b17" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_TermLoanMember_c6341092-f5d4-4047-b833-0664cde7df73" xlink:href="bah-20251231.xsd#bah_TermLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_6e245a4c-84d3-4b7a-9261-1de6e6820b17" xlink:to="loc_bah_TermLoanMember_c6341092-f5d4-4047-b833-0664cde7df73" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_SeniorNotesDue2028Member_c7fed886-562b-491f-9d48-681aa0cd3273" xlink:href="bah-20251231.xsd#bah_SeniorNotesDue2028Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_6e245a4c-84d3-4b7a-9261-1de6e6820b17" xlink:to="loc_bah_SeniorNotesDue2028Member_c7fed886-562b-491f-9d48-681aa0cd3273" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_SeniorNotesDue2029Member_35c05a60-194e-4ca7-b00a-1c84630fe4a7" xlink:href="bah-20251231.xsd#bah_SeniorNotesDue2029Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_6e245a4c-84d3-4b7a-9261-1de6e6820b17" xlink:to="loc_bah_SeniorNotesDue2029Member_35c05a60-194e-4ca7-b00a-1c84630fe4a7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_FivePointNineFivePercentSeniorUnsecuredNotesDue2033Member_ee6f62e3-b920-4c55-9d72-ed5aa81f931a" xlink:href="bah-20251231.xsd#bah_FivePointNineFivePercentSeniorUnsecuredNotesDue2033Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_6e245a4c-84d3-4b7a-9261-1de6e6820b17" xlink:to="loc_bah_FivePointNineFivePercentSeniorUnsecuredNotesDue2033Member_ee6f62e3-b920-4c55-9d72-ed5aa81f931a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_FivePointNineFivePercentSeniorUnsecuredNotesDue2035Member_7766fea7-b198-44f2-b66c-a1f99049af9d" xlink:href="bah-20251231.xsd#bah_FivePointNineFivePercentSeniorUnsecuredNotesDue2035Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_6e245a4c-84d3-4b7a-9261-1de6e6820b17" xlink:to="loc_bah_FivePointNineFivePercentSeniorUnsecuredNotesDue2035Member_7766fea7-b198-44f2-b66c-a1f99049af9d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateEffectivePercentage_59ee8be9-81ed-426a-8e31-382c3d65e625" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentInterestRateEffectivePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_24aaf602-f7b7-42d3-88a8-ced43a28fbf8" xlink:to="loc_us-gaap_DebtInstrumentInterestRateEffectivePercentage_59ee8be9-81ed-426a-8e31-382c3d65e625" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_d99940ce-3559-41d4-8416-2b0d81a015d2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_24aaf602-f7b7-42d3-88a8-ced43a28fbf8" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_d99940ce-3559-41d4-8416-2b0d81a015d2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_e0fe87b6-886d-4043-a2f4-f328845dbe06" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_24aaf602-f7b7-42d3-88a8-ced43a28fbf8" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_e0fe87b6-886d-4043-a2f4-f328845dbe06" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet_d182e40d-eb0d-410d-872b-9b34cc3f4a07" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_24aaf602-f7b7-42d3-88a8-ced43a28fbf8" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet_d182e40d-eb0d-410d-872b-9b34cc3f4a07" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_13a3ebe5-f710-47ef-a198-8b98e6588841" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_24aaf602-f7b7-42d3-88a8-ced43a28fbf8" xlink:to="loc_us-gaap_LongTermDebt_13a3ebe5-f710-47ef-a198-8b98e6588841" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtCurrent_7872ae76-afef-40ae-873a-d3515dcc5c13" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongTermDebtCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_24aaf602-f7b7-42d3-88a8-ced43a28fbf8" xlink:to="loc_us-gaap_LongTermDebtCurrent_7872ae76-afef-40ae-873a-d3515dcc5c13" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtNoncurrent_473f9942-3538-43d6-bca2-b6c9f24df393" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongTermDebtNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_24aaf602-f7b7-42d3-88a8-ced43a28fbf8" xlink:to="loc_us-gaap_LongTermDebtNoncurrent_473f9942-3538-43d6-bca2-b6c9f24df393" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.boozallen.com/role/DebtNarrativeDetails" xlink:type="simple" xlink:href="bah-20251231.xsd#DebtNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/DebtNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_1536c477-21d9-49f4-806e-0450782dce54" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_28e8f92d-1dff-401f-bf1f-bf059021d8d8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_1536c477-21d9-49f4-806e-0450782dce54" xlink:to="loc_us-gaap_DebtInstrumentTable_28e8f92d-1dff-401f-bf1f-bf059021d8d8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_817a0101-b880-4be5-b69b-b9e77495012d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_28e8f92d-1dff-401f-bf1f-bf059021d8d8" xlink:to="loc_us-gaap_DebtInstrumentAxis_817a0101-b880-4be5-b69b-b9e77495012d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_817a0101-b880-4be5-b69b-b9e77495012d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_817a0101-b880-4be5-b69b-b9e77495012d" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_817a0101-b880-4be5-b69b-b9e77495012d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_be2ccc29-ee35-4162-855d-3546e3f56008" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_817a0101-b880-4be5-b69b-b9e77495012d" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_be2ccc29-ee35-4162-855d-3546e3f56008" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_TermLoanMember_62f4c4b0-21d7-46ac-bd6e-4efebf678654" xlink:href="bah-20251231.xsd#bah_TermLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_be2ccc29-ee35-4162-855d-3546e3f56008" xlink:to="loc_bah_TermLoanMember_62f4c4b0-21d7-46ac-bd6e-4efebf678654" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_SecuredCreditFacilityMember_fc099b99-6ef0-424c-a00f-1360c7844508" xlink:href="bah-20251231.xsd#bah_SecuredCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_be2ccc29-ee35-4162-855d-3546e3f56008" xlink:to="loc_bah_SecuredCreditFacilityMember_fc099b99-6ef0-424c-a00f-1360c7844508" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_ec1edc33-952a-4f80-8218-0dbfada6b638" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_28e8f92d-1dff-401f-bf1f-bf059021d8d8" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_ec1edc33-952a-4f80-8218-0dbfada6b638" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_ec1edc33-952a-4f80-8218-0dbfada6b638_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_ec1edc33-952a-4f80-8218-0dbfada6b638" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_ec1edc33-952a-4f80-8218-0dbfada6b638_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_6869cb88-a3eb-4c74-ab29-1ba115ee989d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_ec1edc33-952a-4f80-8218-0dbfada6b638" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_6869cb88-a3eb-4c74-ab29-1ba115ee989d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebtMember_7256cda6-daaa-4756-aea6-e51e9978fbbe" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_6869cb88-a3eb-4c74-ab29-1ba115ee989d" xlink:to="loc_us-gaap_SecuredDebtMember_7256cda6-daaa-4756-aea6-e51e9978fbbe" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_6319a4f4-dd4d-491a-8b18-d29fef3d0876" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_6869cb88-a3eb-4c74-ab29-1ba115ee989d" xlink:to="loc_us-gaap_SeniorNotesMember_6319a4f4-dd4d-491a-8b18-d29fef3d0876" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_3fe95dc9-5a19-4e49-88f8-55380941e7af" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_28e8f92d-1dff-401f-bf1f-bf059021d8d8" xlink:to="loc_us-gaap_CreditFacilityAxis_3fe95dc9-5a19-4e49-88f8-55380941e7af" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_3fe95dc9-5a19-4e49-88f8-55380941e7af_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_3fe95dc9-5a19-4e49-88f8-55380941e7af" xlink:to="loc_us-gaap_CreditFacilityDomain_3fe95dc9-5a19-4e49-88f8-55380941e7af_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_dea98d90-e29c-4a90-ab37-49cefadb3b86" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_3fe95dc9-5a19-4e49-88f8-55380941e7af" xlink:to="loc_us-gaap_CreditFacilityDomain_dea98d90-e29c-4a90-ab37-49cefadb3b86" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_419d6a48-1bac-43ed-a3fc-94611e7284c4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_dea98d90-e29c-4a90-ab37-49cefadb3b86" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_419d6a48-1bac-43ed-a3fc-94611e7284c4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LetterOfCreditMember_2753b375-abf9-49d2-8cae-64e2c7291877" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LetterOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_dea98d90-e29c-4a90-ab37-49cefadb3b86" xlink:to="loc_us-gaap_LetterOfCreditMember_2753b375-abf9-49d2-8cae-64e2c7291877" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_a0a43eb0-9888-4e29-a6c1-0c280013518a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_1536c477-21d9-49f4-806e-0450782dce54" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_a0a43eb0-9888-4e29-a6c1-0c280013518a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_DebtInstrumentNumberOfTranches_6e73cd59-7eeb-4517-a8d8-8cad396167cb" xlink:href="bah-20251231.xsd#bah_DebtInstrumentNumberOfTranches"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_1536c477-21d9-49f4-806e-0450782dce54" xlink:to="loc_bah_DebtInstrumentNumberOfTranches_6e73cd59-7eeb-4517-a8d8-8cad396167cb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromLinesOfCredit_a5831d21-9f60-4434-988d-d8e97532ef71" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProceedsFromLinesOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_1536c477-21d9-49f4-806e-0450782dce54" xlink:to="loc_us-gaap_ProceedsFromLinesOfCredit_a5831d21-9f60-4434-988d-d8e97532ef71" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCredit_ef51d9f4-693a-46c2-8128-d8a4b994b88b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_1536c477-21d9-49f4-806e-0450782dce54" xlink:to="loc_us-gaap_LineOfCredit_ef51d9f4-693a-46c2-8128-d8a4b994b88b" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.boozallen.com/role/IncomeTaxesDetails" xlink:type="simple" xlink:href="bah-20251231.xsd#IncomeTaxesDetails"/>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/IncomeTaxesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TaxCreditCarryforwardLineItems_3ebe0fee-8622-4caa-aa8e-d3f0e6ae03a7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TaxCreditCarryforwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TaxCreditCarryforwardTable_615ed089-2e96-4291-8887-4ebed1fe81d8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TaxCreditCarryforwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_TaxCreditCarryforwardLineItems_3ebe0fee-8622-4caa-aa8e-d3f0e6ae03a7" xlink:to="loc_us-gaap_TaxCreditCarryforwardTable_615ed089-2e96-4291-8887-4ebed1fe81d8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TaxCreditCarryforwardAxis_e449a957-c527-42e2-81ce-28b664660684" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TaxCreditCarryforwardAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_TaxCreditCarryforwardTable_615ed089-2e96-4291-8887-4ebed1fe81d8" xlink:to="loc_us-gaap_TaxCreditCarryforwardAxis_e449a957-c527-42e2-81ce-28b664660684" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TaxCreditCarryforwardNameDomain_e449a957-c527-42e2-81ce-28b664660684_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TaxCreditCarryforwardNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TaxCreditCarryforwardAxis_e449a957-c527-42e2-81ce-28b664660684" xlink:to="loc_us-gaap_TaxCreditCarryforwardNameDomain_e449a957-c527-42e2-81ce-28b664660684_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TaxCreditCarryforwardNameDomain_00cc82b1-de07-4569-8355-76930b97b9c9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TaxCreditCarryforwardNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TaxCreditCarryforwardAxis_e449a957-c527-42e2-81ce-28b664660684" xlink:to="loc_us-gaap_TaxCreditCarryforwardNameDomain_00cc82b1-de07-4569-8355-76930b97b9c9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_ResearchAndDevelopmentTaxCreditsAndDeductionOfForeignDerivedIntangibleIncomeMember_019bb623-90f7-75da-a740-886e996be290" xlink:href="bah-20251231.xsd#bah_ResearchAndDevelopmentTaxCreditsAndDeductionOfForeignDerivedIntangibleIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TaxCreditCarryforwardNameDomain_00cc82b1-de07-4569-8355-76930b97b9c9" xlink:to="loc_bah_ResearchAndDevelopmentTaxCreditsAndDeductionOfForeignDerivedIntangibleIncomeMember_019bb623-90f7-75da-a740-886e996be290" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_ResearchAndDevelopmentTaxCreditsMember_a1d58ff2-e5cf-463c-8b0e-5b4da48e7f49" xlink:href="bah-20251231.xsd#bah_ResearchAndDevelopmentTaxCreditsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TaxCreditCarryforwardNameDomain_00cc82b1-de07-4569-8355-76930b97b9c9" xlink:to="loc_bah_ResearchAndDevelopmentTaxCreditsMember_a1d58ff2-e5cf-463c-8b0e-5b4da48e7f49" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperations_7ab48f85-84b0-4031-8742-87292fcde8a2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EffectiveIncomeTaxRateContinuingOperations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TaxCreditCarryforwardLineItems_3ebe0fee-8622-4caa-aa8e-d3f0e6ae03a7" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperations_7ab48f85-84b0-4031-8742-87292fcde8a2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_019bbcc2-c768-7a4c-b1a9-88f3b9be6590" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TaxCreditCarryforwardLineItems_3ebe0fee-8622-4caa-aa8e-d3f0e6ae03a7" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_019bbcc2-c768-7a4c-b1a9-88f3b9be6590" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForUncertainTaxPositionsNoncurrent_0bcf721f-ff7f-49a7-afae-082335ea2e24" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForUncertainTaxPositionsNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TaxCreditCarryforwardLineItems_3ebe0fee-8622-4caa-aa8e-d3f0e6ae03a7" xlink:to="loc_us-gaap_LiabilityForUncertainTaxPositionsNoncurrent_0bcf721f-ff7f-49a7-afae-082335ea2e24" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_IncreaseDecreaseInIncomeTaxReserves_6a8b17cb-bc85-409b-9478-a5a226d4ace5" xlink:href="bah-20251231.xsd#bah_IncreaseDecreaseInIncomeTaxReserves"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TaxCreditCarryforwardLineItems_3ebe0fee-8622-4caa-aa8e-d3f0e6ae03a7" xlink:to="loc_bah_IncreaseDecreaseInIncomeTaxReserves_6a8b17cb-bc85-409b-9478-a5a226d4ace5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInIncomeTaxesReceivable_1cd1acc5-1a95-4efe-aed4-7f35f80830c5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInIncomeTaxesReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TaxCreditCarryforwardLineItems_3ebe0fee-8622-4caa-aa8e-d3f0e6ae03a7" xlink:to="loc_us-gaap_IncreaseDecreaseInIncomeTaxesReceivable_1cd1acc5-1a95-4efe-aed4-7f35f80830c5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxesReceivableNoncurrent_b54356a4-4d7c-492e-a7f9-5807ca01b814" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxesReceivableNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TaxCreditCarryforwardLineItems_3ebe0fee-8622-4caa-aa8e-d3f0e6ae03a7" xlink:to="loc_us-gaap_IncomeTaxesReceivableNoncurrent_b54356a4-4d7c-492e-a7f9-5807ca01b814" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.boozallen.com/role/AccumulatedOtherComprehensiveLossDetails" xlink:type="simple" xlink:href="bah-20251231.xsd#AccumulatedOtherComprehensiveLossDetails"/>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/AccumulatedOtherComprehensiveLossDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_dfa6436f-71cc-4761-8d40-2ac5ff7c737e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_1861db7b-5975-4d63-b035-535db99a498b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_dfa6436f-71cc-4761-8d40-2ac5ff7c737e" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_1861db7b-5975-4d63-b035-535db99a498b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_bc985ad9-20a3-4f97-b789-83e36bc1570e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_1861db7b-5975-4d63-b035-535db99a498b" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_bc985ad9-20a3-4f97-b789-83e36bc1570e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_bc985ad9-20a3-4f97-b789-83e36bc1570e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_bc985ad9-20a3-4f97-b789-83e36bc1570e" xlink:to="loc_us-gaap_EquityComponentDomain_bc985ad9-20a3-4f97-b789-83e36bc1570e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_3dcdbf32-3a59-4c3b-b722-3ab0bcd5b2a7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_bc985ad9-20a3-4f97-b789-83e36bc1570e" xlink:to="loc_us-gaap_EquityComponentDomain_3dcdbf32-3a59-4c3b-b722-3ab0bcd5b2a7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_83292314-2085-416c-b569-c40bb53ea9c1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_3dcdbf32-3a59-4c3b-b722-3ab0bcd5b2a7" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_83292314-2085-416c-b569-c40bb53ea9c1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember_ece9b4ff-f05f-4a86-8c32-f4270d6f5d93" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_83292314-2085-416c-b569-c40bb53ea9c1" xlink:to="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember_ece9b4ff-f05f-4a86-8c32-f4270d6f5d93" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember_80637790-ba65-410f-b7e4-55b895fe0c49" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_83292314-2085-416c-b569-c40bb53ea9c1" xlink:to="loc_us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember_80637790-ba65-410f-b7e4-55b895fe0c49" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_e89ebed1-773e-4131-ac00-0e129740298a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_dfa6436f-71cc-4761-8d40-2ac5ff7c737e" xlink:to="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_e89ebed1-773e-4131-ac00-0e129740298a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_37cbe641-210f-4202-9190-6cb527a47151" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_e89ebed1-773e-4131-ac00-0e129740298a" xlink:to="loc_us-gaap_StockholdersEquity_37cbe641-210f-4202-9190-6cb527a47151" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OciBeforeReclassificationsBeforeTaxAttributableToParent_7cae91fc-26ea-4aca-a452-122030e66cf0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OciBeforeReclassificationsBeforeTaxAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_e89ebed1-773e-4131-ac00-0e129740298a" xlink:to="loc_us-gaap_OciBeforeReclassificationsBeforeTaxAttributableToParent_7cae91fc-26ea-4aca-a452-122030e66cf0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsTax_4bd4176f-e278-499d-a9eb-654dd70155e5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_e89ebed1-773e-4131-ac00-0e129740298a" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsTax_4bd4176f-e278-499d-a9eb-654dd70155e5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OciBeforeReclassificationsNetOfTaxAttributableToParent_634872fb-109b-4426-9e04-33eedcc57b80" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OciBeforeReclassificationsNetOfTaxAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_e89ebed1-773e-4131-ac00-0e129740298a" xlink:to="loc_us-gaap_OciBeforeReclassificationsNetOfTaxAttributableToParent_634872fb-109b-4426-9e04-33eedcc57b80" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAociCurrentPeriodBeforeTaxAttributableToParent_1994cbe2-2841-4f8f-9215-1b934269e069" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReclassificationFromAociCurrentPeriodBeforeTaxAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_e89ebed1-773e-4131-ac00-0e129740298a" xlink:to="loc_us-gaap_ReclassificationFromAociCurrentPeriodBeforeTaxAttributableToParent_1994cbe2-2841-4f8f-9215-1b934269e069" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAociCurrentPeriodTax_e7540b0c-d3e9-4431-8b9e-a4c24ea5d3e4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReclassificationFromAociCurrentPeriodTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_e89ebed1-773e-4131-ac00-0e129740298a" xlink:to="loc_us-gaap_ReclassificationFromAociCurrentPeriodTax_e7540b0c-d3e9-4431-8b9e-a4c24ea5d3e4" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent_0b7ce6f1-424e-4536-877b-0cac6d9c1b3d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_e89ebed1-773e-4131-ac00-0e129740298a" xlink:to="loc_us-gaap_ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent_0b7ce6f1-424e-4536-877b-0cac6d9c1b3d" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_dded0981-210e-48f4-bd94-7bae005de301" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_e89ebed1-773e-4131-ac00-0e129740298a" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_dded0981-210e-48f4-bd94-7bae005de301" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_374cc50d-9c1d-4c97-979e-d4e04bd3c15e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquity"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.boozallen.com/role/FairValueMeasurementsScheduleofRecurringFairValueMeasurementsDetails" xlink:type="simple" xlink:href="bah-20251231.xsd#FairValueMeasurementsScheduleofRecurringFairValueMeasurementsDetails"/>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/FairValueMeasurementsScheduleofRecurringFairValueMeasurementsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_8dbd797e-7f78-4558-822e-75fac1aebc51" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_0cc8a666-5c33-4c57-a0cf-72a92d13fe8f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_8dbd797e-7f78-4558-822e-75fac1aebc51" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_0cc8a666-5c33-4c57-a0cf-72a92d13fe8f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_a8e4ea95-fa80-4889-96b8-09eeb4348f14" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_0cc8a666-5c33-4c57-a0cf-72a92d13fe8f" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_a8e4ea95-fa80-4889-96b8-09eeb4348f14" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_a8e4ea95-fa80-4889-96b8-09eeb4348f14_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_a8e4ea95-fa80-4889-96b8-09eeb4348f14" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_a8e4ea95-fa80-4889-96b8-09eeb4348f14_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_d3da3ea9-ea31-4a83-abf9-f70e8b472080" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_a8e4ea95-fa80-4889-96b8-09eeb4348f14" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_d3da3ea9-ea31-4a83-abf9-f70e8b472080" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_f544ce76-c2cc-49c8-bb41-baafc3fd4c7b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_d3da3ea9-ea31-4a83-abf9-f70e8b472080" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_f544ce76-c2cc-49c8-bb41-baafc3fd4c7b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_8811bd8e-4460-421f-b402-b61e4e5d27f9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_0cc8a666-5c33-4c57-a0cf-72a92d13fe8f" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_8811bd8e-4460-421f-b402-b61e4e5d27f9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_8811bd8e-4460-421f-b402-b61e4e5d27f9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_8811bd8e-4460-421f-b402-b61e4e5d27f9" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_8811bd8e-4460-421f-b402-b61e4e5d27f9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_d84a6ddc-fafc-4e20-a4fd-40a24979f589" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_8811bd8e-4460-421f-b402-b61e4e5d27f9" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_d84a6ddc-fafc-4e20-a4fd-40a24979f589" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_2b7cb14f-b733-45bf-b493-ccae0a2f8887" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_d84a6ddc-fafc-4e20-a4fd-40a24979f589" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_2b7cb14f-b733-45bf-b493-ccae0a2f8887" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_68de8406-3d03-4552-85aa-678dabcfd08a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_d84a6ddc-fafc-4e20-a4fd-40a24979f589" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_68de8406-3d03-4552-85aa-678dabcfd08a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_b52a9c20-6077-4d5f-9a2a-3188bd639254" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_0cc8a666-5c33-4c57-a0cf-72a92d13fe8f" xlink:to="loc_us-gaap_FinancialInstrumentAxis_b52a9c20-6077-4d5f-9a2a-3188bd639254" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_b52a9c20-6077-4d5f-9a2a-3188bd639254_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_b52a9c20-6077-4d5f-9a2a-3188bd639254" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_b52a9c20-6077-4d5f-9a2a-3188bd639254_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_d2f90dd9-4894-4f26-ab55-73f1ca34b01c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_b52a9c20-6077-4d5f-9a2a-3188bd639254" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_d2f90dd9-4894-4f26-ab55-73f1ca34b01c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MoneyMarketFundsMember_2d7c7361-44e7-4d98-8e5a-4d861553db25" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MoneyMarketFundsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_d2f90dd9-4894-4f26-ab55-73f1ca34b01c" xlink:to="loc_us-gaap_MoneyMarketFundsMember_2d7c7361-44e7-4d98-8e5a-4d861553db25" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosureAbstract_c3c7c4ba-ad8d-474e-8919-ad60643a2660" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetsFairValueDisclosureAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_8dbd797e-7f78-4558-822e-75fac1aebc51" xlink:to="loc_us-gaap_AssetsFairValueDisclosureAbstract_c3c7c4ba-ad8d-474e-8919-ad60643a2660" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_019bca31-411a-732f-be97-091229947cf0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashAndCashEquivalentsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_c3c7c4ba-ad8d-474e-8919-ad60643a2660" xlink:to="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_019bca31-411a-732f-be97-091229947cf0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetsCurrent_41e77843-7815-4d2c-8651-71e0941ba526" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeAssetsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_c3c7c4ba-ad8d-474e-8919-ad60643a2660" xlink:to="loc_us-gaap_DerivativeAssetsCurrent_41e77843-7815-4d2c-8651-71e0941ba526" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredCompensationPlanAssets_7c29e619-9f69-499b-bf07-c5fc6563015e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredCompensationPlanAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_c3c7c4ba-ad8d-474e-8919-ad60643a2660" xlink:to="loc_us-gaap_DeferredCompensationPlanAssets_7c29e619-9f69-499b-bf07-c5fc6563015e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosure_370b013d-6957-4f17-8292-4ac81102c9f1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_c3c7c4ba-ad8d-474e-8919-ad60643a2660" xlink:to="loc_us-gaap_AssetsFairValueDisclosure_370b013d-6957-4f17-8292-4ac81102c9f1" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_753a3f0a-e5f4-4dc2-86a5-9c8370f95ea9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilitiesFairValueDisclosureAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_8dbd797e-7f78-4558-822e-75fac1aebc51" xlink:to="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_753a3f0a-e5f4-4dc2-86a5-9c8370f95ea9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilitiesCurrent_f4ec22cd-094a-46fd-8009-8625f6ef6fef" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeLiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_753a3f0a-e5f4-4dc2-86a5-9c8370f95ea9" xlink:to="loc_us-gaap_DerivativeLiabilitiesCurrent_f4ec22cd-094a-46fd-8009-8625f6ef6fef" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilitiesNoncurrent_b3dc56c1-5ff2-470a-957e-074e3c48d200" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeLiabilitiesNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_753a3f0a-e5f4-4dc2-86a5-9c8370f95ea9" xlink:to="loc_us-gaap_DerivativeLiabilitiesNoncurrent_b3dc56c1-5ff2-470a-957e-074e3c48d200" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredCompensationLiabilityClassifiedNoncurrent_b761da5f-bac8-4bc5-919d-668266ed4b5f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredCompensationLiabilityClassifiedNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_753a3f0a-e5f4-4dc2-86a5-9c8370f95ea9" xlink:to="loc_us-gaap_DeferredCompensationLiabilityClassifiedNoncurrent_b761da5f-bac8-4bc5-919d-668266ed4b5f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialLiabilitiesFairValueDisclosure_2242ddd1-6544-4c26-a401-c314ceb90ce8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialLiabilitiesFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_753a3f0a-e5f4-4dc2-86a5-9c8370f95ea9" xlink:to="loc_us-gaap_FinancialLiabilitiesFairValueDisclosure_2242ddd1-6544-4c26-a401-c314ceb90ce8" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.boozallen.com/role/FairValueMeasurementsNarrativeDetails" xlink:type="simple" xlink:href="bah-20251231.xsd#FairValueMeasurementsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/FairValueMeasurementsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_25fe0fa3-b7fa-4237-8a21-744cd44a114e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_f8e673ca-092e-447d-8ab3-e0ef111a809e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_25fe0fa3-b7fa-4237-8a21-744cd44a114e" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_f8e673ca-092e-447d-8ab3-e0ef111a809e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_774bb238-f223-4227-99e9-73344d1cbf31" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_f8e673ca-092e-447d-8ab3-e0ef111a809e" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_774bb238-f223-4227-99e9-73344d1cbf31" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_774bb238-f223-4227-99e9-73344d1cbf31_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_774bb238-f223-4227-99e9-73344d1cbf31" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_774bb238-f223-4227-99e9-73344d1cbf31_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_bc93b5c6-fdb1-46aa-9223-42ca6055180b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_774bb238-f223-4227-99e9-73344d1cbf31" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_bc93b5c6-fdb1-46aa-9223-42ca6055180b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_019bc6de-c0ed-7559-be2a-1ce3821bde1e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_bc93b5c6-fdb1-46aa-9223-42ca6055180b" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_019bc6de-c0ed-7559-be2a-1ce3821bde1e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsNonrecurringMember_28f481f6-7823-4b57-9391-f01d3b552bbf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsNonrecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_bc93b5c6-fdb1-46aa-9223-42ca6055180b" xlink:to="loc_us-gaap_FairValueMeasurementsNonrecurringMember_28f481f6-7823-4b57-9391-f01d3b552bbf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_76a1d197-b7cf-4973-b1cb-00336916a35a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_f8e673ca-092e-447d-8ab3-e0ef111a809e" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_76a1d197-b7cf-4973-b1cb-00336916a35a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_76a1d197-b7cf-4973-b1cb-00336916a35a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_76a1d197-b7cf-4973-b1cb-00336916a35a" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_76a1d197-b7cf-4973-b1cb-00336916a35a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_beaf8f6a-ca9a-4ed3-a028-0cd01a23335b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_76a1d197-b7cf-4973-b1cb-00336916a35a" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_beaf8f6a-ca9a-4ed3-a028-0cd01a23335b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_99d4d0d1-385b-44f8-906e-62c953e61316" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_beaf8f6a-ca9a-4ed3-a028-0cd01a23335b" xlink:to="loc_us-gaap_InterestRateSwapMember_99d4d0d1-385b-44f8-906e-62c953e61316" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_87e4fd02-6868-4293-9d0e-14cbf4f4c862" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_f8e673ca-092e-447d-8ab3-e0ef111a809e" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_87e4fd02-6868-4293-9d0e-14cbf4f4c862" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_87e4fd02-6868-4293-9d0e-14cbf4f4c862_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_87e4fd02-6868-4293-9d0e-14cbf4f4c862" xlink:to="loc_us-gaap_HedgingRelationshipDomain_87e4fd02-6868-4293-9d0e-14cbf4f4c862_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_68f6e516-3538-4f7c-a3a8-a791af19bce1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_87e4fd02-6868-4293-9d0e-14cbf4f4c862" xlink:to="loc_us-gaap_HedgingRelationshipDomain_68f6e516-3538-4f7c-a3a8-a791af19bce1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashFlowHedgingMember_ea062142-9cf7-4263-a934-a229982a14c2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashFlowHedgingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_68f6e516-3538-4f7c-a3a8-a791af19bce1" xlink:to="loc_us-gaap_CashFlowHedgingMember_ea062142-9cf7-4263-a934-a229982a14c2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_441aa6a8-9933-4183-8253-ef543fe56a78" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_f8e673ca-092e-447d-8ab3-e0ef111a809e" xlink:to="loc_us-gaap_HedgingDesignationAxis_441aa6a8-9933-4183-8253-ef543fe56a78" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_441aa6a8-9933-4183-8253-ef543fe56a78_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_441aa6a8-9933-4183-8253-ef543fe56a78" xlink:to="loc_us-gaap_HedgingDesignationDomain_441aa6a8-9933-4183-8253-ef543fe56a78_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_e2a47a1e-e8c2-4a33-bc82-6cb9c33655ae" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_441aa6a8-9933-4183-8253-ef543fe56a78" xlink:to="loc_us-gaap_HedgingDesignationDomain_e2a47a1e-e8c2-4a33-bc82-6cb9c33655ae" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_a298561f-2b31-4b66-9471-667a43699a98" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DesignatedAsHedgingInstrumentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_e2a47a1e-e8c2-4a33-bc82-6cb9c33655ae" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_a298561f-2b31-4b66-9471-667a43699a98" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_d0a71af6-b5f3-422a-a5b4-75f07585d0f4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_f8e673ca-092e-447d-8ab3-e0ef111a809e" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_d0a71af6-b5f3-422a-a5b4-75f07585d0f4" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_d0a71af6-b5f3-422a-a5b4-75f07585d0f4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_d0a71af6-b5f3-422a-a5b4-75f07585d0f4" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_d0a71af6-b5f3-422a-a5b4-75f07585d0f4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_839feddd-3fc6-474a-a26b-b4b3038eed20" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_d0a71af6-b5f3-422a-a5b4-75f07585d0f4" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_839feddd-3fc6-474a-a26b-b4b3038eed20" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebtMember_ef2919fe-ee4c-4712-8ff0-4517bef5cd24" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_839feddd-3fc6-474a-a26b-b4b3038eed20" xlink:to="loc_us-gaap_SecuredDebtMember_ef2919fe-ee4c-4712-8ff0-4517bef5cd24" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_bee0a8bc-4fae-4aaa-b8d3-bebde791b093" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_f8e673ca-092e-447d-8ab3-e0ef111a809e" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_bee0a8bc-4fae-4aaa-b8d3-bebde791b093" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_bee0a8bc-4fae-4aaa-b8d3-bebde791b093_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_bee0a8bc-4fae-4aaa-b8d3-bebde791b093" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_bee0a8bc-4fae-4aaa-b8d3-bebde791b093_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_122023cb-aa12-4b3f-aebf-c4d427dd196e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_bee0a8bc-4fae-4aaa-b8d3-bebde791b093" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_122023cb-aa12-4b3f-aebf-c4d427dd196e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_3ebfedbd-1b0c-4009-a6ef-6ff91f1126ba" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_122023cb-aa12-4b3f-aebf-c4d427dd196e" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_3ebfedbd-1b0c-4009-a6ef-6ff91f1126ba" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNotionalAmount_195033c5-50ce-4c4f-af20-527a8de599ec" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeNotionalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_25fe0fa3-b7fa-4237-8a21-744cd44a114e" xlink:to="loc_us-gaap_DerivativeNotionalAmount_195033c5-50ce-4c4f-af20-527a8de599ec" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateCashFlowHedgeGainLossToBeReclassifiedDuringNext12MonthsNet_7d45c1d8-3d68-4220-8996-1f36e3a6f203" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestRateCashFlowHedgeGainLossToBeReclassifiedDuringNext12MonthsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_25fe0fa3-b7fa-4237-8a21-744cd44a114e" xlink:to="loc_us-gaap_InterestRateCashFlowHedgeGainLossToBeReclassifiedDuringNext12MonthsNet_7d45c1d8-3d68-4220-8996-1f36e3a6f203" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFairValue_1b99ba78-d676-4bc2-b32e-b563ad886076" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_25fe0fa3-b7fa-4237-8a21-744cd44a114e" xlink:to="loc_us-gaap_DebtInstrumentFairValue_1b99ba78-d676-4bc2-b32e-b563ad886076" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentOwnedAtFairValue_63102cdc-9c13-434a-a144-2a3389966235" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentOwnedAtFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_25fe0fa3-b7fa-4237-8a21-744cd44a114e" xlink:to="loc_us-gaap_InvestmentOwnedAtFairValue_63102cdc-9c13-434a-a144-2a3389966235" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.boozallen.com/role/CommitmentsandContingenciesDetails" xlink:type="simple" xlink:href="bah-20251231.xsd#CommitmentsandContingenciesDetails"/>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/CommitmentsandContingenciesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskLineItems_92b31796-edfd-4160-89d5-f0c61f334654" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTable_e3cf1a58-9d06-4663-a8eb-fc2b3ccb8915" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_92b31796-edfd-4160-89d5-f0c61f334654" xlink:to="loc_us-gaap_ConcentrationRiskTable_e3cf1a58-9d06-4663-a8eb-fc2b3ccb8915" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseAxis_5bd000f9-e39b-4086-abc9-ed455ca54cff" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_LitigationCaseAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_e3cf1a58-9d06-4663-a8eb-fc2b3ccb8915" xlink:to="loc_srt_LitigationCaseAxis_5bd000f9-e39b-4086-abc9-ed455ca54cff" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_5bd000f9-e39b-4086-abc9-ed455ca54cff_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_LitigationCaseAxis_5bd000f9-e39b-4086-abc9-ed455ca54cff" xlink:to="loc_srt_LitigationCaseTypeDomain_5bd000f9-e39b-4086-abc9-ed455ca54cff_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_510914ac-e816-40d1-9406-dbe55a95dd3d" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_LitigationCaseAxis_5bd000f9-e39b-4086-abc9-ed455ca54cff" xlink:to="loc_srt_LitigationCaseTypeDomain_510914ac-e816-40d1-9406-dbe55a95dd3d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_ClaimedIndirectCostsMember_26cb396b-10b2-47bc-96e0-75673923789f" xlink:href="bah-20251231.xsd#bah_ClaimedIndirectCostsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_510914ac-e816-40d1-9406-dbe55a95dd3d" xlink:to="loc_bah_ClaimedIndirectCostsMember_26cb396b-10b2-47bc-96e0-75673923789f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_TriggeringEventAxis_6084108f-da63-4b37-9cdd-3147ecf3afda" xlink:href="bah-20251231.xsd#bah_TriggeringEventAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_e3cf1a58-9d06-4663-a8eb-fc2b3ccb8915" xlink:to="loc_bah_TriggeringEventAxis_6084108f-da63-4b37-9cdd-3147ecf3afda" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_TriggeringEventDomain_6084108f-da63-4b37-9cdd-3147ecf3afda_default" xlink:href="bah-20251231.xsd#bah_TriggeringEventDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_bah_TriggeringEventAxis_6084108f-da63-4b37-9cdd-3147ecf3afda" xlink:to="loc_bah_TriggeringEventDomain_6084108f-da63-4b37-9cdd-3147ecf3afda_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_TriggeringEventDomain_0ec06ae6-ddbe-4772-b789-44729efeb903" xlink:href="bah-20251231.xsd#bah_TriggeringEventDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_bah_TriggeringEventAxis_6084108f-da63-4b37-9cdd-3147ecf3afda" xlink:to="loc_bah_TriggeringEventDomain_0ec06ae6-ddbe-4772-b789-44729efeb903" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_IncreaseToRevenueToReflectBestEstimateOfFinalCostRatesMember_41567316-3532-47ba-8507-cf1fd53d2398" xlink:href="bah-20251231.xsd#bah_IncreaseToRevenueToReflectBestEstimateOfFinalCostRatesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bah_TriggeringEventDomain_0ec06ae6-ddbe-4772-b789-44729efeb903" xlink:to="loc_bah_IncreaseToRevenueToReflectBestEstimateOfFinalCostRatesMember_41567316-3532-47ba-8507-cf1fd53d2398" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019b35e3-ffd6-7048-af4d-791d25aaf044" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_e3cf1a58-9d06-4663-a8eb-fc2b3ccb8915" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019b35e3-ffd6-7048-af4d-791d25aaf044" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019b35e3-ffd6-7048-af4d-791d25aaf044_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019b35e3-ffd6-7048-af4d-791d25aaf044" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019b35e3-ffd6-7048-af4d-791d25aaf044_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019b35e3-ffd6-741f-8bec-ace5311dedee" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019b35e3-ffd6-7048-af4d-791d25aaf044" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019b35e3-ffd6-741f-8bec-ace5311dedee" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BuildingMember_019b6848-471b-7c3c-bfcb-ba6c0d72647b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BuildingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019b35e3-ffd6-741f-8bec-ace5311dedee" xlink:to="loc_us-gaap_BuildingMember_019b6848-471b-7c3c-bfcb-ba6c0d72647b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_TenantImprovementMember_019b685a-8f07-770e-bd49-06b8157f391d" xlink:href="bah-20251231.xsd#bah_TenantImprovementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019b35e3-ffd6-741f-8bec-ace5311dedee" xlink:to="loc_bah_TenantImprovementMember_019b685a-8f07-770e-bd49-06b8157f391d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyAccrualAtCarryingValue_a75da658-86c2-49b9-990b-7dfe4b5b9a89" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingencyAccrualAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_92b31796-edfd-4160-89d5-f0c61f334654" xlink:to="loc_us-gaap_LossContingencyAccrualAtCarryingValue_a75da658-86c2-49b9-990b-7dfe4b5b9a89" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractualObligation_019bbcd2-789f-7c53-87e5-811f2028f4a4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ContractualObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_92b31796-edfd-4160-89d5-f0c61f334654" xlink:to="loc_us-gaap_ContractualObligation_019bbcd2-789f-7c53-87e5-811f2028f4a4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_ContractualObligationTerm_019bbcd8-6e16-7c34-8616-4eb30852f931" xlink:href="bah-20251231.xsd#bah_ContractualObligationTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_92b31796-edfd-4160-89d5-f0c61f334654" xlink:to="loc_bah_ContractualObligationTerm_019bbcd8-6e16-7c34-8616-4eb30852f931" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractualObligationFutureMinimumPaymentsDueRemainderOfFiscalYear_019bbcd3-4614-70ac-bcb0-8c99122688a6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ContractualObligationFutureMinimumPaymentsDueRemainderOfFiscalYear"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_92b31796-edfd-4160-89d5-f0c61f334654" xlink:to="loc_us-gaap_ContractualObligationFutureMinimumPaymentsDueRemainderOfFiscalYear_019bbcd3-4614-70ac-bcb0-8c99122688a6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_LesseeOperatingLeaseNumberOfContracts_019b35e3-ffd6-7cfb-a835-6fd58b78a58d" xlink:href="bah-20251231.xsd#bah_LesseeOperatingLeaseNumberOfContracts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_92b31796-edfd-4160-89d5-f0c61f334654" xlink:to="loc_bah_LesseeOperatingLeaseNumberOfContracts_019b35e3-ffd6-7cfb-a835-6fd58b78a58d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLeaseNotYetCommencedTermOfContract1_019b35e3-ffd6-7cb8-a85c-ffe080ef4ab4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LesseeOperatingLeaseLeaseNotYetCommencedTermOfContract1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_92b31796-edfd-4160-89d5-f0c61f334654" xlink:to="loc_us-gaap_LesseeOperatingLeaseLeaseNotYetCommencedTermOfContract1_019b35e3-ffd6-7cb8-a85c-ffe080ef4ab4" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceSheetAmount_019b35d6-bec7-7c5c-aa7c-c6ce0e8ad69e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceSheetAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_92b31796-edfd-4160-89d5-f0c61f334654" xlink:to="loc_us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceSheetAmount_019b35d6-bec7-7c5c-aa7c-c6ce0e8ad69e" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.boozallen.com/role/SupplementalCondensedConsolidatedFinancialInformationNarrativeDetails" xlink:type="simple" xlink:href="bah-20251231.xsd#SupplementalCondensedConsolidatedFinancialInformationNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/SupplementalCondensedConsolidatedFinancialInformationNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems_019b362b-feab-7176-b772-f87fcb1443f2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringCostAndReserveLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019b362b-feaa-7e2b-b09f-59bfafb7cc9e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019b362b-feab-7176-b772-f87fcb1443f2" xlink:to="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019b362b-feaa-7e2b-b09f-59bfafb7cc9e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveAxis_019bbccb-8719-777e-b2c3-c44d09dc096b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringCostAndReserveAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019b362b-feaa-7e2b-b09f-59bfafb7cc9e" xlink:to="loc_us-gaap_RestructuringCostAndReserveAxis_019bbccb-8719-777e-b2c3-c44d09dc096b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_019bbccb-8719-777e-b2c3-c44d09dc096b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_019bbccb-8719-777e-b2c3-c44d09dc096b" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_019bbccb-8719-777e-b2c3-c44d09dc096b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_019bbccb-8719-731e-903e-815d8eae8c50" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_019bbccb-8719-777e-b2c3-c44d09dc096b" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_019bbccb-8719-731e-903e-815d8eae8c50" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeSeveranceMember_019bbccb-da6a-7ce3-aa26-fda5c4f78695" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeSeveranceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_019bbccb-8719-731e-903e-815d8eae8c50" xlink:to="loc_us-gaap_EmployeeSeveranceMember_019bbccb-da6a-7ce3-aa26-fda5c4f78695" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationAxis_019b6891-238a-78d5-b76b-4d91d1f0205a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupClassificationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019b362b-feaa-7e2b-b09f-59bfafb7cc9e" xlink:to="loc_us-gaap_DisposalGroupClassificationAxis_019b6891-238a-78d5-b76b-4d91d1f0205a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_019b6891-238a-78d5-b76b-4d91d1f0205a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_019b6891-238a-78d5-b76b-4d91d1f0205a" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_019b6891-238a-78d5-b76b-4d91d1f0205a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_019b6891-238a-7e76-b4c7-c8dfe3bc3226" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_019b6891-238a-78d5-b76b-4d91d1f0205a" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_019b6891-238a-7e76-b4c7-c8dfe3bc3226" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember_019b6891-de8c-7bcc-8f75-4ce698649308" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_019b6891-238a-7e76-b4c7-c8dfe3bc3226" xlink:to="loc_us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember_019b6891-de8c-7bcc-8f75-4ce698649308" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019b6893-60d1-73da-b58e-19f09b2ddf3f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019b362b-feaa-7e2b-b09f-59bfafb7cc9e" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019b6893-60d1-73da-b58e-19f09b2ddf3f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019b6893-60d1-73da-b58e-19f09b2ddf3f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019b6893-60d1-73da-b58e-19f09b2ddf3f" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019b6893-60d1-73da-b58e-19f09b2ddf3f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019b6893-60d1-75a0-b20d-4ffa76ccc3db" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019b6893-60d1-73da-b58e-19f09b2ddf3f" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019b6893-60d1-75a0-b20d-4ffa76ccc3db" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_DARPASETAMember_019b8d66-2a27-7c1a-9887-3f9e4df10b82" xlink:href="bah-20251231.xsd#bah_DARPASETAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019b6893-60d1-75a0-b20d-4ffa76ccc3db" xlink:to="loc_bah_DARPASETAMember_019b8d66-2a27-7c1a-9887-3f9e4df10b82" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCharges_65a3c2ee-517f-438b-bdc5-488c8bbbf001" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019b362b-feab-7176-b772-f87fcb1443f2" xlink:to="loc_us-gaap_RestructuringCharges_65a3c2ee-517f-438b-bdc5-488c8bbbf001" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupNotDiscontinuedOperationGainLossOnDisposal_019b362b-3d14-786e-85b7-c2dd5cec4ebb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupNotDiscontinuedOperationGainLossOnDisposal"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019b362b-feab-7176-b772-f87fcb1443f2" xlink:to="loc_us-gaap_DisposalGroupNotDiscontinuedOperationGainLossOnDisposal_019b362b-3d14-786e-85b7-c2dd5cec4ebb" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.boozallen.com/role/SupplementalCondensedConsolidatedFinancialInformationScheduleofSeveranceandRelatedChargesDetails" xlink:type="simple" xlink:href="bah-20251231.xsd#SupplementalCondensedConsolidatedFinancialInformationScheduleofSeveranceandRelatedChargesDetails"/>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/SupplementalCondensedConsolidatedFinancialInformationScheduleofSeveranceandRelatedChargesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems_44528d1d-a883-4d06-af8c-61eab7293c15" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringCostAndReserveLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_407e48b2-39a5-4d89-b416-3c623c40a9cd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_44528d1d-a883-4d06-af8c-61eab7293c15" xlink:to="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_407e48b2-39a5-4d89-b416-3c623c40a9cd" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_ba11ebd0-898b-466c-ae7e-d1e49d340304" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_407e48b2-39a5-4d89-b416-3c623c40a9cd" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_ba11ebd0-898b-466c-ae7e-d1e49d340304" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_ba11ebd0-898b-466c-ae7e-d1e49d340304_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_ba11ebd0-898b-466c-ae7e-d1e49d340304" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_ba11ebd0-898b-466c-ae7e-d1e49d340304_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_83b0d4b7-61e1-4b4d-8694-b30491293a59" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_ba11ebd0-898b-466c-ae7e-d1e49d340304" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_83b0d4b7-61e1-4b4d-8694-b30491293a59" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfSalesMember_129d7c92-c37c-43d3-b884-700281b19c61" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CostOfSalesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_83b0d4b7-61e1-4b4d-8694-b30491293a59" xlink:to="loc_us-gaap_CostOfSalesMember_129d7c92-c37c-43d3-b884-700281b19c61" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpenseMember_716a6f82-72ce-482d-894a-d95173ad1c7b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GeneralAndAdministrativeExpenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_83b0d4b7-61e1-4b4d-8694-b30491293a59" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpenseMember_716a6f82-72ce-482d-894a-d95173ad1c7b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeveranceCosts1_38c16818-c7d8-4308-86c7-0b40ef65a597" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeveranceCosts1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_44528d1d-a883-4d06-af8c-61eab7293c15" xlink:to="loc_us-gaap_SeveranceCosts1_38c16818-c7d8-4308-86c7-0b40ef65a597" xlink:type="arc" order="0"/>
  </link:definitionLink>
</link:linkbase>
