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

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2026 Workiva-->
<!--r:019f13c9-f48e-7aa6-949e-70339bd0aa35,g:c0c3eb3d-7ce2-4cd0-b60b-2aac38d7cacf-->
<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://inhibrx.namespace.com/role/CondensedConsolidatedStatementsofOperations" xlink:type="simple" xlink:href="inhibrx-20260630.xsd#CondensedConsolidatedStatementsofOperations"/>
  <link:definitionLink xlink:role="http://inhibrx.namespace.com/role/CondensedConsolidatedStatementsofOperations" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019f63f9-fd66-7d5a-bce3-672bcfd9535c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_019f63f9-da17-7f31-a8f8-618e55ba4470" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_019f63f9-fd66-7d5a-bce3-672bcfd9535c" xlink:to="loc_us-gaap_StatementTable_019f63f9-da17-7f31-a8f8-618e55ba4470" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_019f63fa-2be4-7eae-9d2f-6dd5446c0e53" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_019f63f9-da17-7f31-a8f8-618e55ba4470" xlink:to="loc_srt_ProductOrServiceAxis_019f63fa-2be4-7eae-9d2f-6dd5446c0e53" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019f63fa-2be4-7eae-9d2f-6dd5446c0e53_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_019f63fa-2be4-7eae-9d2f-6dd5446c0e53" xlink:to="loc_srt_ProductsAndServicesDomain_019f63fa-2be4-7eae-9d2f-6dd5446c0e53_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019f63fa-2be4-7f29-974b-02b9441dbe9d" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_019f63fa-2be4-7eae-9d2f-6dd5446c0e53" xlink:to="loc_srt_ProductsAndServicesDomain_019f63fa-2be4-7f29-974b-02b9441dbe9d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LicenseMember_019f63fa-2be4-738b-a7f4-9f06a7a851b2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LicenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019f63fa-2be4-7f29-974b-02b9441dbe9d" xlink:to="loc_us-gaap_LicenseMember_019f63fa-2be4-738b-a7f4-9f06a7a851b2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenuesAbstract_019f63f9-0273-7507-a74d-51262252f29a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenuesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019f63f9-fd66-7d5a-bce3-672bcfd9535c" xlink:to="loc_us-gaap_RevenuesAbstract_019f63f9-0273-7507-a74d-51262252f29a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_019f63fa-2be4-716a-999a-357337f50776" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesAbstract_019f63f9-0273-7507-a74d-51262252f29a" xlink:to="loc_us-gaap_Revenues_019f63fa-2be4-716a-999a-357337f50776" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingExpensesAbstract_019f13c9-f53e-78c6-89fc-ad42b4c26953" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingExpensesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019f63f9-fd66-7d5a-bce3-672bcfd9535c" xlink:to="loc_us-gaap_OperatingExpensesAbstract_019f13c9-f53e-78c6-89fc-ad42b4c26953" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpense_019f13c9-f53e-7639-ba0d-4886ae2b4018" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ResearchAndDevelopmentExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_019f13c9-f53e-78c6-89fc-ad42b4c26953" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpense_019f13c9-f53e-7639-ba0d-4886ae2b4018" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpense_019f13c9-f53e-7316-969c-ee3ec8f7cf0c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GeneralAndAdministrativeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_019f13c9-f53e-78c6-89fc-ad42b4c26953" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpense_019f13c9-f53e-7316-969c-ee3ec8f7cf0c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingExpenses_019f13c9-f53e-764d-9adc-340af730e75f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_019f13c9-f53e-78c6-89fc-ad42b4c26953" xlink:to="loc_us-gaap_OperatingExpenses_019f13c9-f53e-764d-9adc-340af730e75f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_019f13c9-f53e-74d6-be92-9ebf16e3b6eb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019f63f9-fd66-7d5a-bce3-672bcfd9535c" xlink:to="loc_us-gaap_OperatingIncomeLoss_019f13c9-f53e-74d6-be92-9ebf16e3b6eb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherIncomeAndExpensesAbstract_019f13c9-f53e-7176-b360-6d168c36cd07" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherIncomeAndExpensesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019f63f9-fd66-7d5a-bce3-672bcfd9535c" xlink:to="loc_us-gaap_OtherIncomeAndExpensesAbstract_019f13c9-f53e-7176-b360-6d168c36cd07" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseNonoperating_019f13c9-f53e-7839-bb4c-017f0123887b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestExpenseNonoperating"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherIncomeAndExpensesAbstract_019f13c9-f53e-7176-b360-6d168c36cd07" xlink:to="loc_us-gaap_InterestExpenseNonoperating_019f13c9-f53e-7839-bb4c-017f0123887b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_inhibrx_InterestIncomeNonoperating_019f13c9-f53e-7ef3-ba05-0febd0d60289" xlink:href="inhibrx-20260630.xsd#inhibrx_InterestIncomeNonoperating"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherIncomeAndExpensesAbstract_019f13c9-f53e-7176-b360-6d168c36cd07" xlink:to="loc_inhibrx_InterestIncomeNonoperating_019f13c9-f53e-7ef3-ba05-0febd0d60289" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpense_019f13c9-f53e-7b17-84d0-efb789567972" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherNonoperatingIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherIncomeAndExpensesAbstract_019f13c9-f53e-7176-b360-6d168c36cd07" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpense_019f13c9-f53e-7b17-84d0-efb789567972" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonoperatingIncomeExpense_019f13c9-f53e-7cbb-8d18-1a8e7cccca7e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NonoperatingIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherIncomeAndExpensesAbstract_019f13c9-f53e-7176-b360-6d168c36cd07" xlink:to="loc_us-gaap_NonoperatingIncomeExpense_019f13c9-f53e-7cbb-8d18-1a8e7cccca7e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_019f13c9-f53e-794b-84b8-4562bb9f704c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019f63f9-fd66-7d5a-bce3-672bcfd9535c" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_019f13c9-f53e-794b-84b8-4562bb9f704c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_019f13c9-f53e-7af1-adeb-f878b69feb8b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019f63f9-fd66-7d5a-bce3-672bcfd9535c" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_019f13c9-f53e-7af1-adeb-f878b69feb8b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019f13c9-f53e-7031-ac3d-c3e402ced279" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019f63f9-fd66-7d5a-bce3-672bcfd9535c" xlink:to="loc_us-gaap_NetIncomeLoss_019f13c9-f53e-7031-ac3d-c3e402ced279" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareAbstract_019f13c9-f53e-70f5-9aa8-a0c2b5d79955" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EarningsPerShareAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019f63f9-fd66-7d5a-bce3-672bcfd9535c" xlink:to="loc_us-gaap_EarningsPerShareAbstract_019f13c9-f53e-70f5-9aa8-a0c2b5d79955" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasic_019f13c9-f53e-7b31-9a91-d51285bfb7cb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EarningsPerShareBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareAbstract_019f13c9-f53e-70f5-9aa8-a0c2b5d79955" xlink:to="loc_us-gaap_EarningsPerShareBasic_019f13c9-f53e-7b31-9a91-d51285bfb7cb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDiluted_019f13c9-f53e-7bc3-bfe1-a94ea864975d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EarningsPerShareDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareAbstract_019f13c9-f53e-70f5-9aa8-a0c2b5d79955" xlink:to="loc_us-gaap_EarningsPerShareDiluted_019f13c9-f53e-7bc3-bfe1-a94ea864975d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasicAbstract_019f13c9-f53e-7a11-9a1a-ebe87573bf98" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasicAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019f63f9-fd66-7d5a-bce3-672bcfd9535c" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasicAbstract_019f13c9-f53e-7a11-9a1a-ebe87573bf98" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_019f13c9-f53e-7e42-8ee0-ae9d38250fdf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasicAbstract_019f13c9-f53e-7a11-9a1a-ebe87573bf98" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_019f13c9-f53e-7e42-8ee0-ae9d38250fdf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_019f13c9-f53e-7948-9c26-ac6cf4256a06" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasicAbstract_019f13c9-f53e-7a11-9a1a-ebe87573bf98" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_019f13c9-f53e-7948-9c26-ac6cf4256a06" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://inhibrx.namespace.com/role/CondensedConsolidatedStatementsofStockholdersEquityDeficit" xlink:type="simple" xlink:href="inhibrx-20260630.xsd#CondensedConsolidatedStatementsofStockholdersEquityDeficit"/>
  <link:definitionLink xlink:role="http://inhibrx.namespace.com/role/CondensedConsolidatedStatementsofStockholdersEquityDeficit" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019f13c9-f53e-7dbc-891b-672a006d7ac8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_019f13c9-f53e-7395-a01a-5b5019d55f2e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_019f13c9-f53e-7dbc-891b-672a006d7ac8" xlink:to="loc_us-gaap_StatementTable_019f13c9-f53e-7395-a01a-5b5019d55f2e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_019f13c9-f53e-7a83-8623-2eab9cdf9bdf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_019f13c9-f53e-7395-a01a-5b5019d55f2e" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_019f13c9-f53e-7a83-8623-2eab9cdf9bdf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019f13c9-f53e-7a83-8623-2eab9cdf9bdf_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019f13c9-f53e-7a83-8623-2eab9cdf9bdf" xlink:to="loc_us-gaap_EquityComponentDomain_019f13c9-f53e-7a83-8623-2eab9cdf9bdf_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019f13c9-f53e-7053-9ffd-469422cb22d5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019f13c9-f53e-7a83-8623-2eab9cdf9bdf" xlink:to="loc_us-gaap_EquityComponentDomain_019f13c9-f53e-7053-9ffd-469422cb22d5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_019f13c9-f53e-7903-8026-42b515e596f0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019f13c9-f53e-7053-9ffd-469422cb22d5" xlink:to="loc_us-gaap_CommonStockMember_019f13c9-f53e-7903-8026-42b515e596f0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_019f13c9-f53e-7ee5-ab17-bacc0c67dad5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019f13c9-f53e-7053-9ffd-469422cb22d5" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_019f13c9-f53e-7ee5-ab17-bacc0c67dad5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_019f13c9-f53e-7a2e-8036-41bc2a28bc88" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019f13c9-f53e-7053-9ffd-469422cb22d5" xlink:to="loc_us-gaap_RetainedEarningsMember_019f13c9-f53e-7a2e-8036-41bc2a28bc88" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019f13c9-f53e-7e80-9121-cb3bcd239b41" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019f13c9-f53e-7dbc-891b-672a006d7ac8" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019f13c9-f53e-7e80-9121-cb3bcd239b41" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_019f13c9-f53e-7406-a8a0-82436ee145ba" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019f13c9-f53e-7e80-9121-cb3bcd239b41" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_019f13c9-f53e-7406-a8a0-82436ee145ba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_019f13c9-f53e-712a-b21a-d66b011daf08" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019f13c9-f53e-7e80-9121-cb3bcd239b41" xlink:to="loc_us-gaap_StockholdersEquity_019f13c9-f53e-712a-b21a-d66b011daf08" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_019f13c9-f53e-7fca-899b-540b2aa81042" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019f13c9-f53e-7e80-9121-cb3bcd239b41" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_019f13c9-f53e-7fca-899b-540b2aa81042" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_019f13c9-f53e-7928-9b29-21e713e22ed8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019f13c9-f53e-7e80-9121-cb3bcd239b41" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_019f13c9-f53e-7928-9b29-21e713e22ed8" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_019f13c9-f53e-72e2-a247-1467af809e7e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019f13c9-f53e-7e80-9121-cb3bcd239b41" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_019f13c9-f53e-72e2-a247-1467af809e7e" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalWarrantIssued_019f13c9-f53e-7908-aee5-b98dfeb58ad0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalWarrantIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019f13c9-f53e-7e80-9121-cb3bcd239b41" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalWarrantIssued_019f13c9-f53e-7908-aee5-b98dfeb58ad0" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019f13c9-f53e-7fc0-a5e9-6536f1080efa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019f13c9-f53e-7e80-9121-cb3bcd239b41" xlink:to="loc_us-gaap_NetIncomeLoss_019f13c9-f53e-7fc0-a5e9-6536f1080efa" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_019f13c9-f53e-73dd-82df-b51c6d2719eb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_019f13c9-f53e-7998-b838-b585378635d2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquity"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://inhibrx.namespace.com/role/ORGANIZATIONANDSUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESScheduleofFairValueMeasurementsonaRecurringBasisDetails" xlink:type="simple" xlink:href="inhibrx-20260630.xsd#ORGANIZATIONANDSUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESScheduleofFairValueMeasurementsonaRecurringBasisDetails"/>
  <link:definitionLink xlink:role="http://inhibrx.namespace.com/role/ORGANIZATIONANDSUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESScheduleofFairValueMeasurementsonaRecurringBasisDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_019f13c9-f53e-7989-88c1-6328bed48dc1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable_019f13c9-f53e-7768-be78-3b3b15983726" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_019f13c9-f53e-7989-88c1-6328bed48dc1" xlink:to="loc_us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable_019f13c9-f53e-7768-be78-3b3b15983726" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAxis_019f13c9-f53e-766f-825d-1515063219df" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CashAndCashEquivalentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable_019f13c9-f53e-7768-be78-3b3b15983726" xlink:to="loc_us-gaap_CashAndCashEquivalentsAxis_019f13c9-f53e-766f-825d-1515063219df" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_019f13c9-f53e-766f-825d-1515063219df_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CashAndCashEquivalentsAxis_019f13c9-f53e-766f-825d-1515063219df" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_019f13c9-f53e-766f-825d-1515063219df_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_019f13c9-f53e-70ae-82f7-0b24a8cf1f04" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CashAndCashEquivalentsAxis_019f13c9-f53e-766f-825d-1515063219df" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_019f13c9-f53e-70ae-82f7-0b24a8cf1f04" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MoneyMarketFundsMember_019f13c9-f53e-70ea-93a4-66724af4b494" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MoneyMarketFundsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_019f13c9-f53e-70ae-82f7-0b24a8cf1f04" xlink:to="loc_us-gaap_MoneyMarketFundsMember_019f13c9-f53e-70ea-93a4-66724af4b494" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019f13c9-f53e-7350-b917-95f7c19f0f93" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable_019f13c9-f53e-7768-be78-3b3b15983726" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019f13c9-f53e-7350-b917-95f7c19f0f93" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019f13c9-f53e-7350-b917-95f7c19f0f93_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019f13c9-f53e-7350-b917-95f7c19f0f93" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019f13c9-f53e-7350-b917-95f7c19f0f93_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019f13c9-f53e-796f-b1c4-dd1ca521754f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019f13c9-f53e-7350-b917-95f7c19f0f93" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019f13c9-f53e-796f-b1c4-dd1ca521754f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_019f13c9-f53e-7f33-9bb4-87872cb634bf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019f13c9-f53e-796f-b1c4-dd1ca521754f" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_019f13c9-f53e-7f33-9bb4-87872cb634bf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_019f13c9-f53e-719a-8102-c75415cbe3e8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019f13c9-f53e-796f-b1c4-dd1ca521754f" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_019f13c9-f53e-719a-8102-c75415cbe3e8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_019f13c9-f53e-71aa-b6be-5335392e4ece" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019f13c9-f53e-796f-b1c4-dd1ca521754f" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_019f13c9-f53e-71aa-b6be-5335392e4ece" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_019f13c9-f53e-724e-b2c1-ad918f4fd790" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CashAndCashEquivalentsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_019f13c9-f53e-7989-88c1-6328bed48dc1" xlink:to="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_019f13c9-f53e-724e-b2c1-ad918f4fd790" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://inhibrx.namespace.com/role/ORGANIZATIONANDSUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESScheduleofPotentialDilutiveSecuritiesExcludedfromDilutedLossPerShareDetails" xlink:type="simple" xlink:href="inhibrx-20260630.xsd#ORGANIZATIONANDSUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESScheduleofPotentialDilutiveSecuritiesExcludedfromDilutedLossPerShareDetails"/>
  <link:definitionLink xlink:role="http://inhibrx.namespace.com/role/ORGANIZATIONANDSUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESScheduleofPotentialDilutiveSecuritiesExcludedfromDilutedLossPerShareDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019f13c9-f53e-7fc3-a986-8afab8310d9d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019f13c9-f53e-702c-b7d5-e4ce7d7ea10d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019f13c9-f53e-7fc3-a986-8afab8310d9d" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019f13c9-f53e-702c-b7d5-e4ce7d7ea10d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_019f13c9-f53e-7d1f-907e-6c5d3b7bba62" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019f13c9-f53e-702c-b7d5-e4ce7d7ea10d" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_019f13c9-f53e-7d1f-907e-6c5d3b7bba62" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019f13c9-f53e-7d1f-907e-6c5d3b7bba62_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_019f13c9-f53e-7d1f-907e-6c5d3b7bba62" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019f13c9-f53e-7d1f-907e-6c5d3b7bba62_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019f13c9-f53e-77c6-a72b-ef4bcfae9eeb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_019f13c9-f53e-7d1f-907e-6c5d3b7bba62" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019f13c9-f53e-77c6-a72b-ef4bcfae9eeb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_019f13c9-f53e-713a-9aa6-fb132e15d05d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019f13c9-f53e-77c6-a72b-ef4bcfae9eeb" xlink:to="loc_us-gaap_EmployeeStockOptionMember_019f13c9-f53e-713a-9aa6-fb132e15d05d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WarrantMember_019f13c9-f53e-7605-8e41-9f597c34af3c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WarrantMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019f13c9-f53e-77c6-a72b-ef4bcfae9eeb" xlink:to="loc_us-gaap_WarrantMember_019f13c9-f53e-7605-8e41-9f597c34af3c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_019f13c9-f53e-7010-ab75-950b4dfba187" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019f13c9-f53e-7fc3-a986-8afab8310d9d" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_019f13c9-f53e-7010-ab75-950b4dfba187" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://inhibrx.namespace.com/role/ORGANIZATIONANDSUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESScheduleofSignificantExpenseCategoriesDetails" xlink:type="simple" xlink:href="inhibrx-20260630.xsd#ORGANIZATIONANDSUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESScheduleofSignificantExpenseCategoriesDetails"/>
  <link:definitionLink xlink:role="http://inhibrx.namespace.com/role/ORGANIZATIONANDSUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESScheduleofSignificantExpenseCategoriesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_019f13c9-f53e-7e54-8cca-8ea0862f46d2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019f13c9-f53e-7c12-b52d-84a966e6a7b0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f13c9-f53e-7e54-8cca-8ea0862f46d2" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019f13c9-f53e-7c12-b52d-84a966e6a7b0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019f13c9-f53e-7737-8abb-abc86892b3cb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019f13c9-f53e-7c12-b52d-84a966e6a7b0" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019f13c9-f53e-7737-8abb-abc86892b3cb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019f13c9-f53e-7737-8abb-abc86892b3cb_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019f13c9-f53e-7737-8abb-abc86892b3cb" xlink:to="loc_us-gaap_SegmentDomain_019f13c9-f53e-7737-8abb-abc86892b3cb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019f13c9-f53e-7f19-8160-68653f48689d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019f13c9-f53e-7737-8abb-abc86892b3cb" xlink:to="loc_us-gaap_SegmentDomain_019f13c9-f53e-7f19-8160-68653f48689d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_inhibrx_ReportableSegmentMember_019f13c9-f53e-7220-92e2-2e5a18e953a2" xlink:href="inhibrx-20260630.xsd#inhibrx_ReportableSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019f13c9-f53e-7f19-8160-68653f48689d" xlink:to="loc_inhibrx_ReportableSegmentMember_019f13c9-f53e-7220-92e2-2e5a18e953a2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_019f841e-a321-7f83-86a0-d1b4deb08ba2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f13c9-f53e-7e54-8cca-8ea0862f46d2" xlink:to="loc_us-gaap_Revenues_019f841e-a321-7f83-86a0-d1b4deb08ba2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentAbstract_019f13c9-f53e-788e-95ca-fee50f5ec12e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ResearchAndDevelopmentAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f13c9-f53e-7e54-8cca-8ea0862f46d2" xlink:to="loc_us-gaap_ResearchAndDevelopmentAbstract_019f13c9-f53e-788e-95ca-fee50f5ec12e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_inhibrx_ResearchAndDevelopmentExpensePersonnel_019f13c9-f53e-7cec-8c51-dc2baa10d5af" xlink:href="inhibrx-20260630.xsd#inhibrx_ResearchAndDevelopmentExpensePersonnel"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ResearchAndDevelopmentAbstract_019f13c9-f53e-788e-95ca-fee50f5ec12e" xlink:to="loc_inhibrx_ResearchAndDevelopmentExpensePersonnel_019f13c9-f53e-7cec-8c51-dc2baa10d5af" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_inhibrx_ResearchAndDevelopmentExpenseClinicalTrials_019f13c9-f53e-798c-8a62-5f4805f321a7" xlink:href="inhibrx-20260630.xsd#inhibrx_ResearchAndDevelopmentExpenseClinicalTrials"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ResearchAndDevelopmentAbstract_019f13c9-f53e-788e-95ca-fee50f5ec12e" xlink:to="loc_inhibrx_ResearchAndDevelopmentExpenseClinicalTrials_019f13c9-f53e-798c-8a62-5f4805f321a7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_inhibrx_ResearchAndDevelopmentExpenseContractManufacturing_019f13c9-f53e-7cf8-8385-59b43e010be6" xlink:href="inhibrx-20260630.xsd#inhibrx_ResearchAndDevelopmentExpenseContractManufacturing"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ResearchAndDevelopmentAbstract_019f13c9-f53e-788e-95ca-fee50f5ec12e" xlink:to="loc_inhibrx_ResearchAndDevelopmentExpenseContractManufacturing_019f13c9-f53e-7cf8-8385-59b43e010be6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_inhibrx_ResearchAndDevelopmentExpenseEquipmentDepreciationAndFacility_019f13c9-f53e-792b-9a92-63265289207e" xlink:href="inhibrx-20260630.xsd#inhibrx_ResearchAndDevelopmentExpenseEquipmentDepreciationAndFacility"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ResearchAndDevelopmentAbstract_019f13c9-f53e-788e-95ca-fee50f5ec12e" xlink:to="loc_inhibrx_ResearchAndDevelopmentExpenseEquipmentDepreciationAndFacility_019f13c9-f53e-792b-9a92-63265289207e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherResearchAndDevelopmentExpense_019f13c9-f53e-7e5e-bd54-a70ff001b881" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherResearchAndDevelopmentExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ResearchAndDevelopmentAbstract_019f13c9-f53e-788e-95ca-fee50f5ec12e" xlink:to="loc_us-gaap_OtherResearchAndDevelopmentExpense_019f13c9-f53e-7e5e-bd54-a70ff001b881" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpense_019f13c9-f53e-7a94-b66f-02b8a698848d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ResearchAndDevelopmentExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ResearchAndDevelopmentAbstract_019f13c9-f53e-788e-95ca-fee50f5ec12e" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpense_019f13c9-f53e-7a94-b66f-02b8a698848d" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpenseAbstract_019f13c9-f53e-7d70-acb6-8fbc536cba70" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GeneralAndAdministrativeExpenseAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f13c9-f53e-7e54-8cca-8ea0862f46d2" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpenseAbstract_019f13c9-f53e-7d70-acb6-8fbc536cba70" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_inhibrx_GeneralAndAdministrativeExpensePersonnel_019f13c9-f53e-7cb4-b737-61fd58a32900" xlink:href="inhibrx-20260630.xsd#inhibrx_GeneralAndAdministrativeExpensePersonnel"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GeneralAndAdministrativeExpenseAbstract_019f13c9-f53e-7d70-acb6-8fbc536cba70" xlink:to="loc_inhibrx_GeneralAndAdministrativeExpensePersonnel_019f13c9-f53e-7cb4-b737-61fd58a32900" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherGeneralAndAdministrativeExpense_019f13c9-f53e-7d49-90e9-9bc9b622e57a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherGeneralAndAdministrativeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GeneralAndAdministrativeExpenseAbstract_019f13c9-f53e-7d70-acb6-8fbc536cba70" xlink:to="loc_us-gaap_OtherGeneralAndAdministrativeExpense_019f13c9-f53e-7d49-90e9-9bc9b622e57a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpense_019f13c9-f53e-7b55-a2bb-e5ff62877592" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GeneralAndAdministrativeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GeneralAndAdministrativeExpenseAbstract_019f13c9-f53e-7d70-acb6-8fbc536cba70" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpense_019f13c9-f53e-7b55-a2bb-e5ff62877592" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonoperatingIncomeExpense_019f13c9-f53e-7faa-9370-44b2521cd07b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NonoperatingIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f13c9-f53e-7e54-8cca-8ea0862f46d2" xlink:to="loc_us-gaap_NonoperatingIncomeExpense_019f13c9-f53e-7faa-9370-44b2521cd07b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_019f640a-2b3d-729b-b18e-35c4fa3df83c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f13c9-f53e-7e54-8cca-8ea0862f46d2" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_019f640a-2b3d-729b-b18e-35c4fa3df83c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019f13c9-f53e-7413-9d7e-0cbbbac3f2a8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f13c9-f53e-7e54-8cca-8ea0862f46d2" xlink:to="loc_us-gaap_NetIncomeLoss_019f13c9-f53e-7413-9d7e-0cbbbac3f2a8" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://inhibrx.namespace.com/role/OTHERFINANCIALINFORMATIONScheduleofPropertyandEquipmentNetDetails" xlink:type="simple" xlink:href="inhibrx-20260630.xsd#OTHERFINANCIALINFORMATIONScheduleofPropertyandEquipmentNetDetails"/>
  <link:definitionLink xlink:role="http://inhibrx.namespace.com/role/OTHERFINANCIALINFORMATIONScheduleofPropertyandEquipmentNetDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019f13c9-f53e-73fc-a76c-912f36cb70ec" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_019f13c9-f53e-7db0-964c-d6b2c182d9ad" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019f13c9-f53e-73fc-a76c-912f36cb70ec" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_019f13c9-f53e-7db0-964c-d6b2c182d9ad" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019f13c9-f53e-7d3f-9bc4-83ba997dc7b7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_019f13c9-f53e-7db0-964c-d6b2c182d9ad" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019f13c9-f53e-7d3f-9bc4-83ba997dc7b7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019f13c9-f53e-7d3f-9bc4-83ba997dc7b7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019f13c9-f53e-7d3f-9bc4-83ba997dc7b7" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019f13c9-f53e-7d3f-9bc4-83ba997dc7b7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019f13c9-f53e-7a47-bee8-9a371c92bebd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019f13c9-f53e-7d3f-9bc4-83ba997dc7b7" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019f13c9-f53e-7a47-bee8-9a371c92bebd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MachineryAndEquipmentMember_019f13c9-f53e-7d5c-8166-e031ef6a3c1b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MachineryAndEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019f13c9-f53e-7a47-bee8-9a371c92bebd" xlink:to="loc_us-gaap_MachineryAndEquipmentMember_019f13c9-f53e-7d5c-8166-e031ef6a3c1b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SoftwareDevelopmentMember_019f13c9-f53e-7f64-bbe8-4cc54f0486c1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SoftwareDevelopmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019f13c9-f53e-7a47-bee8-9a371c92bebd" xlink:to="loc_us-gaap_SoftwareDevelopmentMember_019f13c9-f53e-7f64-bbe8-4cc54f0486c1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeaseholdImprovementsMember_019f13c9-f53e-724a-b241-aa023075c22d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LeaseholdImprovementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019f13c9-f53e-7a47-bee8-9a371c92bebd" xlink:to="loc_us-gaap_LeaseholdImprovementsMember_019f13c9-f53e-724a-b241-aa023075c22d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FurnitureAndFixturesMember_019f13c9-f53e-7d1d-b7ad-74f54212267a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FurnitureAndFixturesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019f13c9-f53e-7a47-bee8-9a371c92bebd" xlink:to="loc_us-gaap_FurnitureAndFixturesMember_019f13c9-f53e-7d1d-b7ad-74f54212267a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross_019f13c9-f53e-79ba-be19-110b07007fd3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019f13c9-f53e-73fc-a76c-912f36cb70ec" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentGross_019f13c9-f53e-79ba-be19-110b07007fd3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_019f13c9-f53e-794e-8403-084bf59f26c9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019f13c9-f53e-73fc-a76c-912f36cb70ec" xlink:to="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_019f13c9-f53e-794e-8403-084bf59f26c9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_019f13c9-f53e-7260-8a71-8cdfab7b66b0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019f13c9-f53e-73fc-a76c-912f36cb70ec" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_019f13c9-f53e-7260-8a71-8cdfab7b66b0" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://inhibrx.namespace.com/role/OTHERFINANCIALINFORMATIONScheduleofDepreciationandAmortizationExpenseDetails" xlink:type="simple" xlink:href="inhibrx-20260630.xsd#OTHERFINANCIALINFORMATIONScheduleofDepreciationandAmortizationExpenseDetails"/>
  <link:definitionLink xlink:role="http://inhibrx.namespace.com/role/OTHERFINANCIALINFORMATIONScheduleofDepreciationandAmortizationExpenseDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019f13c9-f53e-76bb-93a1-2dab68da4470" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_019f13c9-f53e-79a6-9127-998e2f7ba89d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019f13c9-f53e-76bb-93a1-2dab68da4470" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_019f13c9-f53e-79a6-9127-998e2f7ba89d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019f13c9-f53e-7d17-aa8e-6239840a078f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementOfIncomeLocationBalanceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_019f13c9-f53e-79a6-9127-998e2f7ba89d" xlink:to="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019f13c9-f53e-7d17-aa8e-6239840a078f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepreciationDepletionAndAmortization_019f13c9-f53e-7c90-bee7-10cffa92153e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DepreciationDepletionAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019f13c9-f53e-76bb-93a1-2dab68da4470" xlink:to="loc_us-gaap_DepreciationDepletionAndAmortization_019f13c9-f53e-7c90-bee7-10cffa92153e" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://inhibrx.namespace.com/role/OTHERFINANCIALINFORMATIONScheduleofDepreciationandAmortizationExpenseDetails_1" xlink:type="simple" xlink:href="inhibrx-20260630.xsd#OTHERFINANCIALINFORMATIONScheduleofDepreciationandAmortizationExpenseDetails_1"/>
  <link:definitionLink xlink:role="http://inhibrx.namespace.com/role/OTHERFINANCIALINFORMATIONScheduleofDepreciationandAmortizationExpenseDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019f13c9-f53e-76bb-93a1-2dab68da4470" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_019f13c9-f53e-79a6-9127-998e2f7ba89d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019f13c9-f53e-76bb-93a1-2dab68da4470" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_019f13c9-f53e-79a6-9127-998e2f7ba89d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepreciationDepletionAndAmortization_019f13c9-f53e-7c90-bee7-10cffa92153e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DepreciationDepletionAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019f13c9-f53e-76bb-93a1-2dab68da4470" xlink:to="loc_us-gaap_DepreciationDepletionAndAmortization_019f13c9-f53e-7c90-bee7-10cffa92153e" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://inhibrx.namespace.com/role/DEBTNarrativeDetails" xlink:type="simple" xlink:href="inhibrx-20260630.xsd#DEBTNarrativeDetails"/>
  <link:definitionLink xlink:role="http://inhibrx.namespace.com/role/DEBTNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_019f13c9-f53e-79b6-b3c3-3ecf3c3c6d84" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_019f13c9-f53e-741e-bee1-9301dec41bce" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f13c9-f53e-79b6-b3c3-3ecf3c3c6d84" xlink:to="loc_us-gaap_DebtInstrumentTable_019f13c9-f53e-741e-bee1-9301dec41bce" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_019f13c9-f53e-76cd-ad82-0e58fdb69f8d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019f13c9-f53e-741e-bee1-9301dec41bce" xlink:to="loc_us-gaap_CreditFacilityAxis_019f13c9-f53e-76cd-ad82-0e58fdb69f8d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019f13c9-f53e-76cd-ad82-0e58fdb69f8d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_019f13c9-f53e-76cd-ad82-0e58fdb69f8d" xlink:to="loc_us-gaap_CreditFacilityDomain_019f13c9-f53e-76cd-ad82-0e58fdb69f8d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019f13c9-f53e-79c4-b701-594900fc7cbd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_019f13c9-f53e-76cd-ad82-0e58fdb69f8d" xlink:to="loc_us-gaap_CreditFacilityDomain_019f13c9-f53e-79c4-b701-594900fc7cbd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebtMember_019f13c9-f53e-7bf2-8433-ccbb6d7ca13e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019f13c9-f53e-79c4-b701-594900fc7cbd" xlink:to="loc_us-gaap_SecuredDebtMember_019f13c9-f53e-7bf2-8433-ccbb6d7ca13e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019f13c9-f53e-7a4c-8b8b-6653059e2b81" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019f13c9-f53e-741e-bee1-9301dec41bce" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019f13c9-f53e-7a4c-8b8b-6653059e2b81" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019f13c9-f53e-7a4c-8b8b-6653059e2b81_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019f13c9-f53e-7a4c-8b8b-6653059e2b81" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019f13c9-f53e-7a4c-8b8b-6653059e2b81_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019f13c9-f53e-7ccf-ba95-6e90c6bbac73" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019f13c9-f53e-7a4c-8b8b-6653059e2b81" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019f13c9-f53e-7ccf-ba95-6e90c6bbac73" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_019f13c9-f53e-73fc-ab64-e82dba60f42a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f13c9-f53e-7ccf-ba95-6e90c6bbac73" xlink:to="loc_us-gaap_LineOfCreditMember_019f13c9-f53e-73fc-ab64-e82dba60f42a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebtMember_019f13c9-f53e-7289-b5d6-9f2eab27e102" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f13c9-f53e-7ccf-ba95-6e90c6bbac73" xlink:to="loc_us-gaap_SecuredDebtMember_019f13c9-f53e-7289-b5d6-9f2eab27e102" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019f13c9-f53e-7e29-9629-d4e223b98bc3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019f13c9-f53e-741e-bee1-9301dec41bce" xlink:to="loc_us-gaap_DebtInstrumentAxis_019f13c9-f53e-7e29-9629-d4e223b98bc3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019f13c9-f53e-7e29-9629-d4e223b98bc3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_019f13c9-f53e-7e29-9629-d4e223b98bc3" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019f13c9-f53e-7e29-9629-d4e223b98bc3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019f13c9-f53e-7156-91b5-7837e714d2a4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_019f13c9-f53e-7e29-9629-d4e223b98bc3" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019f13c9-f53e-7156-91b5-7837e714d2a4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_inhibrx_OxfordTermLoansMember_019f13c9-f53e-7696-bde4-017106194e25" xlink:href="inhibrx-20260630.xsd#inhibrx_OxfordTermLoansMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019f13c9-f53e-7156-91b5-7837e714d2a4" xlink:to="loc_inhibrx_OxfordTermLoansMember_019f13c9-f53e-7696-bde4-017106194e25" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_inhibrx_OxfordWarrants2025Member_019f13c9-f53e-7f70-9fd6-f0f42f88366a" xlink:href="inhibrx-20260630.xsd#inhibrx_OxfordWarrants2025Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019f13c9-f53e-7156-91b5-7837e714d2a4" xlink:to="loc_inhibrx_OxfordWarrants2025Member_019f13c9-f53e-7f70-9fd6-f0f42f88366a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_inhibrx_OxfordWarrants2026Member_019f13c9-f53e-7bff-9542-2d04862a7b5e" xlink:href="inhibrx-20260630.xsd#inhibrx_OxfordWarrants2026Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019f13c9-f53e-7156-91b5-7837e714d2a4" xlink:to="loc_inhibrx_OxfordWarrants2026Member_019f13c9-f53e-7bff-9542-2d04862a7b5e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019f13c9-f53e-73c9-ace9-afcb3882e63c" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019f13c9-f53e-741e-bee1-9301dec41bce" xlink:to="loc_srt_RangeAxis_019f13c9-f53e-73c9-ace9-afcb3882e63c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019f13c9-f53e-73c9-ace9-afcb3882e63c_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019f13c9-f53e-73c9-ace9-afcb3882e63c" xlink:to="loc_srt_RangeMember_019f13c9-f53e-73c9-ace9-afcb3882e63c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019f13c9-f53e-7e88-8c0f-1bf9827e7b1f" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019f13c9-f53e-73c9-ace9-afcb3882e63c" xlink:to="loc_srt_RangeMember_019f13c9-f53e-7e88-8c0f-1bf9827e7b1f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019f13c9-f53e-7484-abb0-6d5d73ebef19" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019f13c9-f53e-7e88-8c0f-1bf9827e7b1f" xlink:to="loc_srt_MinimumMember_019f13c9-f53e-7484-abb0-6d5d73ebef19" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019f13c9-f53e-7624-adc0-3d724ac00b2d" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019f13c9-f53e-7e88-8c0f-1bf9827e7b1f" xlink:to="loc_srt_MaximumMember_019f13c9-f53e-7624-adc0-3d724ac00b2d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfLongTermDebt_019f13c9-f53e-7768-aee4-fae01bc5e189" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromIssuanceOfLongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f13c9-f53e-79b6-b3c3-3ecf3c3c6d84" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfLongTermDebt_019f13c9-f53e-7768-aee4-fae01bc5e189" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_inhibrx_LineOfCreditFacilityMaximumBorrowingCapacityAccordionFeature_019f13c9-f53e-7c2e-9b60-852757e2d374" xlink:href="inhibrx-20260630.xsd#inhibrx_LineOfCreditFacilityMaximumBorrowingCapacityAccordionFeature"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f13c9-f53e-79b6-b3c3-3ecf3c3c6d84" xlink:to="loc_inhibrx_LineOfCreditFacilityMaximumBorrowingCapacityAccordionFeature_019f13c9-f53e-7c2e-9b60-852757e2d374" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_019f13c9-f53e-7ec3-ba4b-447c2b350819" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f13c9-f53e-79b6-b3c3-3ecf3c3c6d84" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_019f13c9-f53e-7ec3-ba4b-447c2b350819" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_019f13c9-f53e-7da8-b15b-074b55e20578" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f13c9-f53e-79b6-b3c3-3ecf3c3c6d84" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_019f13c9-f53e-7da8-b15b-074b55e20578" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019f13c9-f53e-7613-bc76-2065c826a1d5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f13c9-f53e-79b6-b3c3-3ecf3c3c6d84" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019f13c9-f53e-7613-bc76-2065c826a1d5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_inhibrx_DebtInstrumentPrincipalAndInterestTerm_019f13c9-f53e-7d9a-912c-947e771745d5" xlink:href="inhibrx-20260630.xsd#inhibrx_DebtInstrumentPrincipalAndInterestTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f13c9-f53e-79b6-b3c3-3ecf3c3c6d84" xlink:to="loc_inhibrx_DebtInstrumentPrincipalAndInterestTerm_019f13c9-f53e-7d9a-912c-947e771745d5" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_inhibrx_DebtInstrumentPeriodicPaymentTermsBalloonPaymentToBePaidPercent_019f13c9-f53e-7b19-a753-ff3effe42509" xlink:href="inhibrx-20260630.xsd#inhibrx_DebtInstrumentPeriodicPaymentTermsBalloonPaymentToBePaidPercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f13c9-f53e-79b6-b3c3-3ecf3c3c6d84" xlink:to="loc_inhibrx_DebtInstrumentPeriodicPaymentTermsBalloonPaymentToBePaidPercent_019f13c9-f53e-7b19-a753-ff3effe42509" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentPeriodicPaymentTermsBalloonPaymentToBePaid_019f13c9-f53e-7f7c-b6b1-c8012c030d5d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentPeriodicPaymentTermsBalloonPaymentToBePaid"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f13c9-f53e-79b6-b3c3-3ecf3c3c6d84" xlink:to="loc_us-gaap_DebtInstrumentPeriodicPaymentTermsBalloonPaymentToBePaid_019f13c9-f53e-7f7c-b6b1-c8012c030d5d" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_inhibrx_DebtInstrumentPrepaymentFee_019f13c9-f53e-7e15-b977-41b540a3626a" xlink:href="inhibrx-20260630.xsd#inhibrx_DebtInstrumentPrepaymentFee"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f13c9-f53e-79b6-b3c3-3ecf3c3c6d84" xlink:to="loc_inhibrx_DebtInstrumentPrepaymentFee_019f13c9-f53e-7e15-b977-41b540a3626a" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_inhibrx_LongTermDebtLiquidityThreshold_019f13c9-f53e-7786-a7a1-2c31a91f4328" xlink:href="inhibrx-20260630.xsd#inhibrx_LongTermDebtLiquidityThreshold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f13c9-f53e-79b6-b3c3-3ecf3c3c6d84" xlink:to="loc_inhibrx_LongTermDebtLiquidityThreshold_019f13c9-f53e-7786-a7a1-2c31a91f4328" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights_019f13c9-f53e-78c7-ad04-3427505876eb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f13c9-f53e-79b6-b3c3-3ecf3c3c6d84" xlink:to="loc_us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights_019f13c9-f53e-78c7-ad04-3427505876eb" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_019f13c9-f53e-7eed-bb63-0c377804ec38" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f13c9-f53e-79b6-b3c3-3ecf3c3c6d84" xlink:to="loc_us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_019f13c9-f53e-7eed-bb63-0c377804ec38" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WarrantsAndRightsOutstandingTerm_019f13c9-f53e-7394-b1d6-62fc5a90612c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WarrantsAndRightsOutstandingTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f13c9-f53e-79b6-b3c3-3ecf3c3c6d84" xlink:to="loc_us-gaap_WarrantsAndRightsOutstandingTerm_019f13c9-f53e-7394-b1d6-62fc5a90612c" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalWarrantIssued_019f13c9-f53e-718b-997a-f89b641f045c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalWarrantIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f13c9-f53e-79b6-b3c3-3ecf3c3c6d84" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalWarrantIssued_019f13c9-f53e-718b-997a-f89b641f045c" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateEffectivePercentage_019f13c9-f53e-712b-b104-2a1a9fbbcbad" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentInterestRateEffectivePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f13c9-f53e-79b6-b3c3-3ecf3c3c6d84" xlink:to="loc_us-gaap_DebtInstrumentInterestRateEffectivePercentage_019f13c9-f53e-712b-b104-2a1a9fbbcbad" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseDebt_019f13c9-f53e-715b-9399-26ca8d184677" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestExpenseDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f13c9-f53e-79b6-b3c3-3ecf3c3c6d84" xlink:to="loc_us-gaap_InterestExpenseDebt_019f13c9-f53e-715b-9399-26ca8d184677" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfDebtDiscountPremium_019f13c9-f53e-7166-bc55-605cb051455c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AmortizationOfDebtDiscountPremium"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f13c9-f53e-79b6-b3c3-3ecf3c3c6d84" xlink:to="loc_us-gaap_AmortizationOfDebtDiscountPremium_019f13c9-f53e-7166-bc55-605cb051455c" xlink:type="arc" order="16"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://inhibrx.namespace.com/role/DEBTScheduleofLongTermDebtDetails" xlink:type="simple" xlink:href="inhibrx-20260630.xsd#DEBTScheduleofLongTermDebtDetails"/>
  <link:definitionLink xlink:role="http://inhibrx.namespace.com/role/DEBTScheduleofLongTermDebtDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_019f13c9-f53e-762d-81d6-c1ae2c8354e8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_019f13c9-f53e-7bff-84f2-8f22bdda27e2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f13c9-f53e-762d-81d6-c1ae2c8354e8" xlink:to="loc_us-gaap_DebtInstrumentTable_019f13c9-f53e-7bff-84f2-8f22bdda27e2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019f13c9-f53e-75ef-9a92-da8aa3afab0e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019f13c9-f53e-7bff-84f2-8f22bdda27e2" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019f13c9-f53e-75ef-9a92-da8aa3afab0e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019f13c9-f53e-75ef-9a92-da8aa3afab0e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019f13c9-f53e-75ef-9a92-da8aa3afab0e" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019f13c9-f53e-75ef-9a92-da8aa3afab0e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019f13c9-f53e-714a-88a4-5b100bd02789" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019f13c9-f53e-75ef-9a92-da8aa3afab0e" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019f13c9-f53e-714a-88a4-5b100bd02789" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_019f13c9-f53e-7999-a3d5-f25a9e62ec99" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f13c9-f53e-714a-88a4-5b100bd02789" xlink:to="loc_us-gaap_LineOfCreditMember_019f13c9-f53e-7999-a3d5-f25a9e62ec99" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_019f13c9-f53e-7295-9204-284d89b420b6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019f13c9-f53e-7bff-84f2-8f22bdda27e2" xlink:to="loc_us-gaap_CreditFacilityAxis_019f13c9-f53e-7295-9204-284d89b420b6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019f13c9-f53e-7295-9204-284d89b420b6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_019f13c9-f53e-7295-9204-284d89b420b6" xlink:to="loc_us-gaap_CreditFacilityDomain_019f13c9-f53e-7295-9204-284d89b420b6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019f13c9-f53e-7b09-8abb-67cc75eacf4d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_019f13c9-f53e-7295-9204-284d89b420b6" xlink:to="loc_us-gaap_CreditFacilityDomain_019f13c9-f53e-7b09-8abb-67cc75eacf4d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebtMember_019f13c9-f53e-7f19-87aa-5b829081302e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019f13c9-f53e-7b09-8abb-67cc75eacf4d" xlink:to="loc_us-gaap_SecuredDebtMember_019f13c9-f53e-7f19-87aa-5b829081302e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019f13c9-f53e-76c2-b051-747be799a381" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019f13c9-f53e-7bff-84f2-8f22bdda27e2" xlink:to="loc_us-gaap_DebtInstrumentAxis_019f13c9-f53e-76c2-b051-747be799a381" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019f13c9-f53e-76c2-b051-747be799a381_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_019f13c9-f53e-76c2-b051-747be799a381" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019f13c9-f53e-76c2-b051-747be799a381_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019f13c9-f53e-72c4-82a6-27f3bcabac61" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_019f13c9-f53e-76c2-b051-747be799a381" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019f13c9-f53e-72c4-82a6-27f3bcabac61" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_inhibrx_TermLoanAMember_019f13c9-f53e-79b3-a80a-7c10da2dfeb0" xlink:href="inhibrx-20260630.xsd#inhibrx_TermLoanAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019f13c9-f53e-72c4-82a6-27f3bcabac61" xlink:to="loc_inhibrx_TermLoanAMember_019f13c9-f53e-79b3-a80a-7c10da2dfeb0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_inhibrx_TermLoanBMember_019f13c9-f53e-7812-8db7-d6a3a78c59ad" xlink:href="inhibrx-20260630.xsd#inhibrx_TermLoanBMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019f13c9-f53e-72c4-82a6-27f3bcabac61" xlink:to="loc_inhibrx_TermLoanBMember_019f13c9-f53e-7812-8db7-d6a3a78c59ad" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_019f13c9-f53e-79c9-80c8-e836929d5b7e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f13c9-f53e-762d-81d6-c1ae2c8354e8" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_019f13c9-f53e-79c9-80c8-e836929d5b7e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscount_019f13c9-f53e-7f21-b24d-a466920a7e6d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentUnamortizedDiscount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f13c9-f53e-762d-81d6-c1ae2c8354e8" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedDiscount_019f13c9-f53e-7f21-b24d-a466920a7e6d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_019f13c9-f53e-7c2f-8512-a036fe5c6a81" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f13c9-f53e-762d-81d6-c1ae2c8354e8" xlink:to="loc_us-gaap_LongTermDebt_019f13c9-f53e-7c2f-8512-a036fe5c6a81" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://inhibrx.namespace.com/role/DEBTScheduleofMaturitiesofLongTermDebtDetails" xlink:type="simple" xlink:href="inhibrx-20260630.xsd#DEBTScheduleofMaturitiesofLongTermDebtDetails"/>
  <link:definitionLink xlink:role="http://inhibrx.namespace.com/role/DEBTScheduleofMaturitiesofLongTermDebtDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_019f13c9-f53e-71c3-af7b-9f01c8a9b509" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_019f13c9-f53e-7306-96f9-2b186b547156" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f13c9-f53e-71c3-af7b-9f01c8a9b509" xlink:to="loc_us-gaap_DebtInstrumentTable_019f13c9-f53e-7306-96f9-2b186b547156" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019f13c9-f53e-7967-bd43-8ea2c2b7dd05" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019f13c9-f53e-7306-96f9-2b186b547156" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019f13c9-f53e-7967-bd43-8ea2c2b7dd05" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019f13c9-f53e-7967-bd43-8ea2c2b7dd05_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019f13c9-f53e-7967-bd43-8ea2c2b7dd05" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019f13c9-f53e-7967-bd43-8ea2c2b7dd05_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019f13c9-f53e-78c8-890e-e629c09d59ec" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019f13c9-f53e-7967-bd43-8ea2c2b7dd05" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019f13c9-f53e-78c8-890e-e629c09d59ec" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_019f13c9-f53e-76d3-84f3-1aa3464f6406" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f13c9-f53e-78c8-890e-e629c09d59ec" xlink:to="loc_us-gaap_LineOfCreditMember_019f13c9-f53e-76d3-84f3-1aa3464f6406" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_019f13c9-f53e-7865-99cd-de1f9643e289" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019f13c9-f53e-7306-96f9-2b186b547156" xlink:to="loc_us-gaap_CreditFacilityAxis_019f13c9-f53e-7865-99cd-de1f9643e289" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019f13c9-f53e-7865-99cd-de1f9643e289_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_019f13c9-f53e-7865-99cd-de1f9643e289" xlink:to="loc_us-gaap_CreditFacilityDomain_019f13c9-f53e-7865-99cd-de1f9643e289_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019f13c9-f53e-7c19-91ac-5f1648c501f0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_019f13c9-f53e-7865-99cd-de1f9643e289" xlink:to="loc_us-gaap_CreditFacilityDomain_019f13c9-f53e-7c19-91ac-5f1648c501f0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebtMember_019f13c9-f53e-711e-85cf-10388e15d550" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019f13c9-f53e-7c19-91ac-5f1648c501f0" xlink:to="loc_us-gaap_SecuredDebtMember_019f13c9-f53e-711e-85cf-10388e15d550" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo_019f13c9-f53e-77b7-bd81-c5f393f1eab1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f13c9-f53e-71c3-af7b-9f01c8a9b509" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo_019f13c9-f53e-77b7-bd81-c5f393f1eab1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree_019f13c9-f53e-7688-9776-4c778251126e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f13c9-f53e-71c3-af7b-9f01c8a9b509" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree_019f13c9-f53e-7688-9776-4c778251126e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_inhibrx_LongTermDebtMaturityAfterYearThree_019f13c9-f53e-7108-8fa2-64d6980599bc" xlink:href="inhibrx-20260630.xsd#inhibrx_LongTermDebtMaturityAfterYearThree"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f13c9-f53e-71c3-af7b-9f01c8a9b509" xlink:to="loc_inhibrx_LongTermDebtMaturityAfterYearThree_019f13c9-f53e-7108-8fa2-64d6980599bc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_019f13c9-f53e-77c0-a6e7-8d5938e96110" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f13c9-f53e-71c3-af7b-9f01c8a9b509" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_019f13c9-f53e-77c0-a6e7-8d5938e96110" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscount_019f13c9-f53e-7772-9cee-8edc674275a1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentUnamortizedDiscount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f13c9-f53e-71c3-af7b-9f01c8a9b509" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedDiscount_019f13c9-f53e-7772-9cee-8edc674275a1" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_019f13c9-f53e-7a98-8673-c0a4998697b9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f13c9-f53e-71c3-af7b-9f01c8a9b509" xlink:to="loc_us-gaap_LongTermDebt_019f13c9-f53e-7a98-8673-c0a4998697b9" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://inhibrx.namespace.com/role/STOCKHOLDERSEQUITYDEFICITNarrativeDetails" xlink:type="simple" xlink:href="inhibrx-20260630.xsd#STOCKHOLDERSEQUITYDEFICITNarrativeDetails"/>
  <link:definitionLink xlink:role="http://inhibrx.namespace.com/role/STOCKHOLDERSEQUITYDEFICITNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f13c9-f53e-7cd7-8b68-e6ba0a774446" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019f13c9-f53e-7001-885d-23e74c8b0d04" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f13c9-f53e-7cd7-8b68-e6ba0a774446" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019f13c9-f53e-7001-885d-23e74c8b0d04" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightAxis_019f13c9-f53e-7841-b33a-a3af5fee75f8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019f13c9-f53e-7001-885d-23e74c8b0d04" xlink:to="loc_us-gaap_ClassOfWarrantOrRightAxis_019f13c9-f53e-7841-b33a-a3af5fee75f8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightDomain_019f13c9-f53e-7841-b33a-a3af5fee75f8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ClassOfWarrantOrRightAxis_019f13c9-f53e-7841-b33a-a3af5fee75f8" xlink:to="loc_us-gaap_ClassOfWarrantOrRightDomain_019f13c9-f53e-7841-b33a-a3af5fee75f8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightDomain_019f13c9-f53e-708f-bc33-f5682be69daf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ClassOfWarrantOrRightAxis_019f13c9-f53e-7841-b33a-a3af5fee75f8" xlink:to="loc_us-gaap_ClassOfWarrantOrRightDomain_019f13c9-f53e-708f-bc33-f5682be69daf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_inhibrx_WarrantsPreFundedMember_019f13c9-f53e-7b02-b36c-480f46fb7b77" xlink:href="inhibrx-20260630.xsd#inhibrx_WarrantsPreFundedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightDomain_019f13c9-f53e-708f-bc33-f5682be69daf" xlink:to="loc_inhibrx_WarrantsPreFundedMember_019f13c9-f53e-7b02-b36c-480f46fb7b77" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsidiarySaleOfStockAxis_019f13c9-f53e-78da-9cfe-a4640696443e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsidiarySaleOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019f13c9-f53e-7001-885d-23e74c8b0d04" xlink:to="loc_us-gaap_SubsidiarySaleOfStockAxis_019f13c9-f53e-78da-9cfe-a4640696443e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_019f13c9-f53e-78da-9cfe-a4640696443e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_019f13c9-f53e-78da-9cfe-a4640696443e" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_019f13c9-f53e-78da-9cfe-a4640696443e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_019f13c9-f53e-70ea-bf4a-c748d5036974" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_019f13c9-f53e-78da-9cfe-a4640696443e" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_019f13c9-f53e-70ea-bf4a-c748d5036974" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PrivatePlacementMember_019f13c9-f53e-7398-af9b-eba5df9b432f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PrivatePlacementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SaleOfStockNameOfTransactionDomain_019f13c9-f53e-70ea-bf4a-c748d5036974" xlink:to="loc_us-gaap_PrivatePlacementMember_019f13c9-f53e-7398-af9b-eba5df9b432f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019f13c9-f53e-7119-960f-44bfa4c7b17d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019f13c9-f53e-7001-885d-23e74c8b0d04" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019f13c9-f53e-7119-960f-44bfa4c7b17d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019f13c9-f53e-7119-960f-44bfa4c7b17d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019f13c9-f53e-7119-960f-44bfa4c7b17d" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019f13c9-f53e-7119-960f-44bfa4c7b17d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019f13c9-f53e-77e8-8e62-52f3a9cfa614" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019f13c9-f53e-7119-960f-44bfa4c7b17d" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019f13c9-f53e-77e8-8e62-52f3a9cfa614" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebtMember_019f13c9-f53e-792d-9225-9437c6967f84" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f13c9-f53e-77e8-8e62-52f3a9cfa614" xlink:to="loc_us-gaap_SecuredDebtMember_019f13c9-f53e-792d-9225-9437c6967f84" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_inhibrx_ClassOfWarrantOrRightPurchasePriceOfWarrantsOrRights1_019f13c9-f53e-7958-9dff-e69760b04cb4" xlink:href="inhibrx-20260630.xsd#inhibrx_ClassOfWarrantOrRightPurchasePriceOfWarrantsOrRights1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f13c9-f53e-7cd7-8b68-e6ba0a774446" xlink:to="loc_inhibrx_ClassOfWarrantOrRightPurchasePriceOfWarrantsOrRights1_019f13c9-f53e-7958-9dff-e69760b04cb4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_019f13c9-f53e-77d9-b856-5c4db167b7b3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f13c9-f53e-7cd7-8b68-e6ba0a774446" xlink:to="loc_us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_019f13c9-f53e-77d9-b856-5c4db167b7b3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights_019f13c9-f53e-7a61-8868-7fd8a86c5c7d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f13c9-f53e-7cd7-8b68-e6ba0a774446" xlink:to="loc_us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights_019f13c9-f53e-7a61-8868-7fd8a86c5c7d" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://inhibrx.namespace.com/role/STOCKHOLDERSEQUITYDEFICITScheduleofCommonStockReservedforFutureIssuanceDetails" xlink:type="simple" xlink:href="inhibrx-20260630.xsd#STOCKHOLDERSEQUITYDEFICITScheduleofCommonStockReservedforFutureIssuanceDetails"/>
  <link:definitionLink xlink:role="http://inhibrx.namespace.com/role/STOCKHOLDERSEQUITYDEFICITScheduleofCommonStockReservedforFutureIssuanceDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f13c9-f53e-7d05-838a-d848b035b24d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019f13c9-f53e-724e-a2d2-4f53ffbff9c9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f13c9-f53e-7d05-838a-d848b035b24d" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019f13c9-f53e-724e-a2d2-4f53ffbff9c9" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019f13c9-f53e-725e-9b41-31854ed1b964" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019f13c9-f53e-724e-a2d2-4f53ffbff9c9" xlink:to="loc_us-gaap_AwardTypeAxis_019f13c9-f53e-725e-9b41-31854ed1b964" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f13c9-f53e-725e-9b41-31854ed1b964_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_019f13c9-f53e-725e-9b41-31854ed1b964" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f13c9-f53e-725e-9b41-31854ed1b964_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f13c9-f53e-7918-9fb2-771ef64ae5c9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_019f13c9-f53e-725e-9b41-31854ed1b964" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f13c9-f53e-7918-9fb2-771ef64ae5c9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_019f13c9-f53e-744d-ad43-9792653c7d2d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f13c9-f53e-7918-9fb2-771ef64ae5c9" xlink:to="loc_us-gaap_EmployeeStockOptionMember_019f13c9-f53e-744d-ad43-9792653c7d2d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockCompensationPlanMember_019f13c9-f53e-73bb-8d08-5909152cfa4f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockCompensationPlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f13c9-f53e-7918-9fb2-771ef64ae5c9" xlink:to="loc_us-gaap_StockCompensationPlanMember_019f13c9-f53e-73bb-8d08-5909152cfa4f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_inhibrx_PreFundedWarrantsMember_019f13c9-f53e-744a-bf4e-44f5174b1dbb" xlink:href="inhibrx-20260630.xsd#inhibrx_PreFundedWarrantsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f13c9-f53e-7918-9fb2-771ef64ae5c9" xlink:to="loc_inhibrx_PreFundedWarrantsMember_019f13c9-f53e-744a-bf4e-44f5174b1dbb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WarrantMember_019f13c9-f53e-7ca6-9e29-2c411dcb303f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WarrantMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f13c9-f53e-7918-9fb2-771ef64ae5c9" xlink:to="loc_us-gaap_WarrantMember_019f13c9-f53e-7ca6-9e29-2c411dcb303f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_019f13c9-f53e-7226-a6fe-a7015bf16d2b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockCapitalSharesReservedForFutureIssuance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f13c9-f53e-7d05-838a-d848b035b24d" xlink:to="loc_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_019f13c9-f53e-7226-a6fe-a7015bf16d2b" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://inhibrx.namespace.com/role/EQUITYCOMPENSATIONPLANNarrativeDetails" xlink:type="simple" xlink:href="inhibrx-20260630.xsd#EQUITYCOMPENSATIONPLANNarrativeDetails"/>
  <link:definitionLink xlink:role="http://inhibrx.namespace.com/role/EQUITYCOMPENSATIONPLANNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f13c9-f5e5-74a2-8f84-2a7b7575fd59" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019f13c9-f5e5-7dde-8428-d35e7e444750" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f13c9-f5e5-74a2-8f84-2a7b7575fd59" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019f13c9-f5e5-7dde-8428-d35e7e444750" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_019f13c9-f5e5-7f31-b6cd-4c075780f568" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019f13c9-f5e5-7dde-8428-d35e7e444750" xlink:to="loc_us-gaap_PlanNameAxis_019f13c9-f5e5-7f31-b6cd-4c075780f568" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_019f13c9-f5e5-7f31-b6cd-4c075780f568_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_019f13c9-f5e5-7f31-b6cd-4c075780f568" xlink:to="loc_us-gaap_PlanNameDomain_019f13c9-f5e5-7f31-b6cd-4c075780f568_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_019f13c9-f5e5-77f3-91c3-10718cd3d6fc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_019f13c9-f5e5-7f31-b6cd-4c075780f568" xlink:to="loc_us-gaap_PlanNameDomain_019f13c9-f5e5-77f3-91c3-10718cd3d6fc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_inhibrx_A2024PlanMember_019f13c9-f5e5-7b35-b502-1a6ce4227c00" xlink:href="inhibrx-20260630.xsd#inhibrx_A2024PlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_019f13c9-f5e5-77f3-91c3-10718cd3d6fc" xlink:to="loc_inhibrx_A2024PlanMember_019f13c9-f5e5-7b35-b502-1a6ce4227c00" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019f13c9-f5e5-7856-990a-5f0c877ddc68" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019f13c9-f5e5-7dde-8428-d35e7e444750" xlink:to="loc_us-gaap_AwardTypeAxis_019f13c9-f5e5-7856-990a-5f0c877ddc68" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f13c9-f5e5-7856-990a-5f0c877ddc68_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_019f13c9-f5e5-7856-990a-5f0c877ddc68" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f13c9-f5e5-7856-990a-5f0c877ddc68_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f13c9-f5e5-7084-9932-83e0cea37630" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_019f13c9-f5e5-7856-990a-5f0c877ddc68" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f13c9-f5e5-7084-9932-83e0cea37630" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_019f13c9-f5e5-7339-bc61-63d80af4ad50" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f13c9-f5e5-7084-9932-83e0cea37630" xlink:to="loc_us-gaap_EmployeeStockOptionMember_019f13c9-f5e5-7339-bc61-63d80af4ad50" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingAxis_019f13c9-f5e5-7bf4-9876-3faf33711645" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_VestingAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019f13c9-f5e5-7dde-8428-d35e7e444750" xlink:to="loc_us-gaap_VestingAxis_019f13c9-f5e5-7bf4-9876-3faf33711645" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingDomain_019f13c9-f5e5-7bf4-9876-3faf33711645_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_VestingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VestingAxis_019f13c9-f5e5-7bf4-9876-3faf33711645" xlink:to="loc_us-gaap_VestingDomain_019f13c9-f5e5-7bf4-9876-3faf33711645_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingDomain_019f13c9-f5e5-7342-a515-118066612e21" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_VestingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VestingAxis_019f13c9-f5e5-7bf4-9876-3faf33711645" xlink:to="loc_us-gaap_VestingDomain_019f13c9-f5e5-7342-a515-118066612e21" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationAwardTrancheOneMember_019f13c9-f5e5-7b51-92f7-bc17a621f2ba" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationAwardTrancheOneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_019f13c9-f5e5-7342-a515-118066612e21" xlink:to="loc_us-gaap_ShareBasedCompensationAwardTrancheOneMember_019f13c9-f5e5-7b51-92f7-bc17a621f2ba" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_019f13c9-f5e5-752b-8e8c-a434893f2227" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f13c9-f5e5-74a2-8f84-2a7b7575fd59" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_019f13c9-f5e5-752b-8e8c-a434893f2227" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_019f13c9-f5e5-7b3a-b6bb-4440dcd485fa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f13c9-f5e5-74a2-8f84-2a7b7575fd59" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_019f13c9-f5e5-7b3a-b6bb-4440dcd485fa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_019f13c9-f5e5-72d2-876e-ab60ed41715b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f13c9-f5e5-74a2-8f84-2a7b7575fd59" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_019f13c9-f5e5-72d2-876e-ab60ed41715b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_019f13c9-f5e5-7505-93a6-e004f60ab600" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f13c9-f5e5-74a2-8f84-2a7b7575fd59" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_019f13c9-f5e5-7505-93a6-e004f60ab600" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_019f13c9-f5e5-7b95-b2b0-a0adf15b8a50" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f13c9-f5e5-74a2-8f84-2a7b7575fd59" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_019f13c9-f5e5-7b95-b2b0-a0adf15b8a50" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1_019f13c9-f5e5-7e5a-a58b-1001d766f955" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f13c9-f5e5-74a2-8f84-2a7b7575fd59" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1_019f13c9-f5e5-7e5a-a58b-1001d766f955" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_019f13c9-f5e5-7c8f-ac7a-da5d00a11096" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f13c9-f5e5-74a2-8f84-2a7b7575fd59" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_019f13c9-f5e5-7c8f-ac7a-da5d00a11096" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_019f13c9-f5e5-7eab-a930-8ae71fd118fd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f13c9-f5e5-74a2-8f84-2a7b7575fd59" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_019f13c9-f5e5-7eab-a930-8ae71fd118fd" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://inhibrx.namespace.com/role/EQUITYCOMPENSATIONPLANScheduleofStockOptionsActivityDetails" xlink:type="simple" xlink:href="inhibrx-20260630.xsd#EQUITYCOMPENSATIONPLANScheduleofStockOptionsActivityDetails"/>
  <link:definitionLink xlink:role="http://inhibrx.namespace.com/role/EQUITYCOMPENSATIONPLANScheduleofStockOptionsActivityDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f13c9-f5e5-78d6-b916-e8e42762fb14" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019f13c9-f5e5-7c6b-b9dc-043e77e7f233" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f13c9-f5e5-78d6-b916-e8e42762fb14" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019f13c9-f5e5-7c6b-b9dc-043e77e7f233" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_019f13c9-f5e5-7c76-a842-5f382d18dff5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019f13c9-f5e5-7c6b-b9dc-043e77e7f233" xlink:to="loc_us-gaap_PlanNameAxis_019f13c9-f5e5-7c76-a842-5f382d18dff5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_019f13c9-f5e5-7c76-a842-5f382d18dff5_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_019f13c9-f5e5-7c76-a842-5f382d18dff5" xlink:to="loc_us-gaap_PlanNameDomain_019f13c9-f5e5-7c76-a842-5f382d18dff5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_019f13c9-f5e5-7c81-9836-c2ba46324dad" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_019f13c9-f5e5-7c76-a842-5f382d18dff5" xlink:to="loc_us-gaap_PlanNameDomain_019f13c9-f5e5-7c81-9836-c2ba46324dad" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_inhibrx_A2024PlanMember_019f13c9-f5e5-7bfd-96d2-d998af1a9207" xlink:href="inhibrx-20260630.xsd#inhibrx_A2024PlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_019f13c9-f5e5-7c81-9836-c2ba46324dad" xlink:to="loc_inhibrx_A2024PlanMember_019f13c9-f5e5-7bfd-96d2-d998af1a9207" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_019f13c9-f5e5-75e0-9973-4ce90c899555" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f13c9-f5e5-78d6-b916-e8e42762fb14" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_019f13c9-f5e5-75e0-9973-4ce90c899555" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_019f13c9-f5e5-7895-8b61-a137ed464e87" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_019f13c9-f5e5-75e0-9973-4ce90c899555" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_019f13c9-f5e5-7895-8b61-a137ed464e87" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_019fa7d9-662e-758a-b4bb-3e651e277468" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_019f13c9-f5e5-75e0-9973-4ce90c899555" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_019fa7d9-662e-758a-b4bb-3e651e277468" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_019f13c9-f5e5-71ad-8fce-1f5529630b04" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_019f13c9-f5e5-75e0-9973-4ce90c899555" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_019f13c9-f5e5-71ad-8fce-1f5529630b04" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod_019f13c9-f5e5-7e1d-bc44-477eaf9ad1ed" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_019f13c9-f5e5-75e0-9973-4ce90c899555" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod_019f13c9-f5e5-7e1d-bc44-477eaf9ad1ed" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_019f13c9-f5e5-707e-8f93-b086ea407840" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber_019f13c9-f5e5-7994-ae83-46459f7a5454" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f13c9-f5e5-78d6-b916-e8e42762fb14" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber_019f13c9-f5e5-7994-ae83-46459f7a5454" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_019f13c9-f5e5-761b-a7f1-a64dacdab5fe" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f13c9-f5e5-78d6-b916-e8e42762fb14" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_019f13c9-f5e5-761b-a7f1-a64dacdab5fe" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_019f13c9-f5e5-7e51-b282-4bef6a9b8e7b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_019f13c9-f5e5-761b-a7f1-a64dacdab5fe" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_019f13c9-f5e5-7e51-b282-4bef6a9b8e7b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_019fa7d9-662e-75ba-804a-256c73252825" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_019f13c9-f5e5-761b-a7f1-a64dacdab5fe" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_019fa7d9-662e-75ba-804a-256c73252825" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_019f13c9-f5e5-7d79-a465-8dd994ea1182" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_019f13c9-f5e5-761b-a7f1-a64dacdab5fe" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_019f13c9-f5e5-7d79-a465-8dd994ea1182" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice_019f13c9-f5e5-70e9-bd08-e6f0ee8390a9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_019f13c9-f5e5-761b-a7f1-a64dacdab5fe" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice_019f13c9-f5e5-70e9-bd08-e6f0ee8390a9" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_019f13c9-f5e5-7060-ba0f-a2c5c0967996" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageExercisePrice_019f13c9-f5e5-704f-81ed-2c42e4510c66" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f13c9-f5e5-78d6-b916-e8e42762fb14" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageExercisePrice_019f13c9-f5e5-704f-81ed-2c42e4510c66" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_019f13c9-f5e5-73fa-aacb-4b4c6cf11781" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f13c9-f5e5-78d6-b916-e8e42762fb14" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_019f13c9-f5e5-73fa-aacb-4b4c6cf11781" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue_019f13c9-f5e5-7406-9701-3b2235ac8876" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f13c9-f5e5-78d6-b916-e8e42762fb14" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue_019f13c9-f5e5-7406-9701-3b2235ac8876" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageRemainingContractualTerm1_019f13c9-f5e5-77e4-b528-52876690076c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageRemainingContractualTerm1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f13c9-f5e5-78d6-b916-e8e42762fb14" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageRemainingContractualTerm1_019f13c9-f5e5-77e4-b528-52876690076c" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableAggregateIntrinsicValue_019f13c9-f5e5-79ad-ada0-74bb68d0d165" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableAggregateIntrinsicValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f13c9-f5e5-78d6-b916-e8e42762fb14" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableAggregateIntrinsicValue_019f13c9-f5e5-79ad-ada0-74bb68d0d165" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://inhibrx.namespace.com/role/EQUITYCOMPENSATIONPLANScheduleofWeightedAverageAssumptionsUsedtoEstimateFairValueDetails" xlink:type="simple" xlink:href="inhibrx-20260630.xsd#EQUITYCOMPENSATIONPLANScheduleofWeightedAverageAssumptionsUsedtoEstimateFairValueDetails"/>
  <link:definitionLink xlink:role="http://inhibrx.namespace.com/role/EQUITYCOMPENSATIONPLANScheduleofWeightedAverageAssumptionsUsedtoEstimateFairValueDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f13c9-f5e5-70bc-9bdc-cdd7f617f02d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019f13c9-f5e5-7532-90f1-8c0145c7fbd1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f13c9-f5e5-70bc-9bdc-cdd7f617f02d" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019f13c9-f5e5-7532-90f1-8c0145c7fbd1" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019f13c9-f5e5-7c17-aacc-4e592c1f1825" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019f13c9-f5e5-7532-90f1-8c0145c7fbd1" xlink:to="loc_us-gaap_AwardTypeAxis_019f13c9-f5e5-7c17-aacc-4e592c1f1825" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f13c9-f5e5-7c17-aacc-4e592c1f1825_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_019f13c9-f5e5-7c17-aacc-4e592c1f1825" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f13c9-f5e5-7c17-aacc-4e592c1f1825_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f13c9-f5e5-7f55-b119-b1705e73ac0d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_019f13c9-f5e5-7c17-aacc-4e592c1f1825" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f13c9-f5e5-7f55-b119-b1705e73ac0d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_019f13c9-f5e5-75b1-8435-ef5b0ea24609" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f13c9-f5e5-7f55-b119-b1705e73ac0d" xlink:to="loc_us-gaap_EmployeeStockOptionMember_019f13c9-f5e5-75b1-8435-ef5b0ea24609" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_019f13c9-f5e5-77a3-aa97-b68a2beb720e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f13c9-f5e5-70bc-9bdc-cdd7f617f02d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_019f13c9-f5e5-77a3-aa97-b68a2beb720e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_019f13c9-f5e5-7e46-aa21-2e2015c611b0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f13c9-f5e5-70bc-9bdc-cdd7f617f02d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_019f13c9-f5e5-7e46-aa21-2e2015c611b0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_019f13c9-f5e5-7018-b466-5e8d48816781" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f13c9-f5e5-70bc-9bdc-cdd7f617f02d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_019f13c9-f5e5-7018-b466-5e8d48816781" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_019f13c9-f5e5-7dd1-8582-f59d6948df31" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f13c9-f5e5-70bc-9bdc-cdd7f617f02d" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_019f13c9-f5e5-7dd1-8582-f59d6948df31" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_019f13c9-f5e5-702c-a4e1-96872e1c1bf4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f13c9-f5e5-70bc-9bdc-cdd7f617f02d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_019f13c9-f5e5-702c-a4e1-96872e1c1bf4" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://inhibrx.namespace.com/role/EQUITYCOMPENSATIONPLANScheduleofStockBasedCompensationExpenseDetails" xlink:type="simple" xlink:href="inhibrx-20260630.xsd#EQUITYCOMPENSATIONPLANScheduleofStockBasedCompensationExpenseDetails"/>
  <link:definitionLink xlink:role="http://inhibrx.namespace.com/role/EQUITYCOMPENSATIONPLANScheduleofStockBasedCompensationExpenseDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f13c9-f5e5-7ded-9cc9-0bb3ef088133" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019f13c9-f5e5-7eb5-bc92-66c2e9e0a9c0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f13c9-f5e5-7ded-9cc9-0bb3ef088133" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019f13c9-f5e5-7eb5-bc92-66c2e9e0a9c0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019f13c9-f5e5-7cda-b166-dff1121d8ec4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementOfIncomeLocationBalanceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019f13c9-f5e5-7eb5-bc92-66c2e9e0a9c0" xlink:to="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019f13c9-f5e5-7cda-b166-dff1121d8ec4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019f13c9-f5e5-7aec-b8e7-bef27b1707e9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019f13c9-f5e5-7eb5-bc92-66c2e9e0a9c0" xlink:to="loc_us-gaap_AwardTypeAxis_019f13c9-f5e5-7aec-b8e7-bef27b1707e9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f13c9-f5e5-7aec-b8e7-bef27b1707e9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_019f13c9-f5e5-7aec-b8e7-bef27b1707e9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f13c9-f5e5-7aec-b8e7-bef27b1707e9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f13c9-f5e5-74ac-b829-6b6de3dedf60" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_019f13c9-f5e5-7aec-b8e7-bef27b1707e9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f13c9-f5e5-74ac-b829-6b6de3dedf60" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_019f13c9-f5e5-7446-b6ac-9fc37158def3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f13c9-f5e5-74ac-b829-6b6de3dedf60" xlink:to="loc_us-gaap_EmployeeStockOptionMember_019f13c9-f5e5-7446-b6ac-9fc37158def3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_019f13c9-f5e5-79d0-9736-21c240e501b2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019f13c9-f5e5-7eb5-bc92-66c2e9e0a9c0" xlink:to="loc_us-gaap_PlanNameAxis_019f13c9-f5e5-79d0-9736-21c240e501b2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_019f13c9-f5e5-79d0-9736-21c240e501b2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_019f13c9-f5e5-79d0-9736-21c240e501b2" xlink:to="loc_us-gaap_PlanNameDomain_019f13c9-f5e5-79d0-9736-21c240e501b2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_019f13c9-f5e5-7d98-ae07-513604fa8f80" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_019f13c9-f5e5-79d0-9736-21c240e501b2" xlink:to="loc_us-gaap_PlanNameDomain_019f13c9-f5e5-7d98-ae07-513604fa8f80" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_inhibrx_A2024PlanMember_019f13c9-f5e5-73ed-99f1-b820d56b95d3" xlink:href="inhibrx-20260630.xsd#inhibrx_A2024PlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_019f13c9-f5e5-7d98-ae07-513604fa8f80" xlink:to="loc_inhibrx_A2024PlanMember_019f13c9-f5e5-73ed-99f1-b820d56b95d3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_019f13c9-f5e5-753e-99e1-8799bd73d9e4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f13c9-f5e5-7ded-9cc9-0bb3ef088133" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_019f13c9-f5e5-753e-99e1-8799bd73d9e4" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://inhibrx.namespace.com/role/EQUITYCOMPENSATIONPLANScheduleofStockBasedCompensationExpenseDetails_1" xlink:type="simple" xlink:href="inhibrx-20260630.xsd#EQUITYCOMPENSATIONPLANScheduleofStockBasedCompensationExpenseDetails_1"/>
  <link:definitionLink xlink:role="http://inhibrx.namespace.com/role/EQUITYCOMPENSATIONPLANScheduleofStockBasedCompensationExpenseDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f13c9-f5e5-7ded-9cc9-0bb3ef088133" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019f13c9-f5e5-7eb5-bc92-66c2e9e0a9c0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f13c9-f5e5-7ded-9cc9-0bb3ef088133" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019f13c9-f5e5-7eb5-bc92-66c2e9e0a9c0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019f13c9-f5e5-7aec-b8e7-bef27b1707e9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019f13c9-f5e5-7eb5-bc92-66c2e9e0a9c0" xlink:to="loc_us-gaap_AwardTypeAxis_019f13c9-f5e5-7aec-b8e7-bef27b1707e9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f13c9-f5e5-7aec-b8e7-bef27b1707e9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_019f13c9-f5e5-7aec-b8e7-bef27b1707e9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f13c9-f5e5-7aec-b8e7-bef27b1707e9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f13c9-f5e5-74ac-b829-6b6de3dedf60" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_019f13c9-f5e5-7aec-b8e7-bef27b1707e9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f13c9-f5e5-74ac-b829-6b6de3dedf60" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_019f13c9-f5e5-7446-b6ac-9fc37158def3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f13c9-f5e5-74ac-b829-6b6de3dedf60" xlink:to="loc_us-gaap_EmployeeStockOptionMember_019f13c9-f5e5-7446-b6ac-9fc37158def3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_019f13c9-f5e5-79d0-9736-21c240e501b2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019f13c9-f5e5-7eb5-bc92-66c2e9e0a9c0" xlink:to="loc_us-gaap_PlanNameAxis_019f13c9-f5e5-79d0-9736-21c240e501b2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_019f13c9-f5e5-79d0-9736-21c240e501b2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_019f13c9-f5e5-79d0-9736-21c240e501b2" xlink:to="loc_us-gaap_PlanNameDomain_019f13c9-f5e5-79d0-9736-21c240e501b2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_019f13c9-f5e5-7d98-ae07-513604fa8f80" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_019f13c9-f5e5-79d0-9736-21c240e501b2" xlink:to="loc_us-gaap_PlanNameDomain_019f13c9-f5e5-7d98-ae07-513604fa8f80" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_inhibrx_A2024PlanMember_019f13c9-f5e5-73ed-99f1-b820d56b95d3" xlink:href="inhibrx-20260630.xsd#inhibrx_A2024PlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_019f13c9-f5e5-7d98-ae07-513604fa8f80" xlink:to="loc_inhibrx_A2024PlanMember_019f13c9-f5e5-73ed-99f1-b820d56b95d3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_019f13c9-f5e5-753e-99e1-8799bd73d9e4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f13c9-f5e5-7ded-9cc9-0bb3ef088133" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_019f13c9-f5e5-753e-99e1-8799bd73d9e4" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://inhibrx.namespace.com/role/LICENSEREVENUESScheduleofLicenseandGrantRevenueDetails" xlink:type="simple" xlink:href="inhibrx-20260630.xsd#LICENSEREVENUESScheduleofLicenseandGrantRevenueDetails"/>
  <link:definitionLink xlink:role="http://inhibrx.namespace.com/role/LICENSEREVENUESScheduleofLicenseandGrantRevenueDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_019f13c9-f5e5-7874-bace-1d7d8784f387" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable_019f13c9-f5e5-727f-ac65-32533b802d15" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_019f13c9-f5e5-7874-bace-1d7d8784f387" xlink:to="loc_us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable_019f13c9-f5e5-727f-ac65-32533b802d15" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_019f13c9-f5e5-748b-86fa-c6c713c64331" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable_019f13c9-f5e5-727f-ac65-32533b802d15" xlink:to="loc_srt_ProductOrServiceAxis_019f13c9-f5e5-748b-86fa-c6c713c64331" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019f13c9-f5e5-748b-86fa-c6c713c64331_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_019f13c9-f5e5-748b-86fa-c6c713c64331" xlink:to="loc_srt_ProductsAndServicesDomain_019f13c9-f5e5-748b-86fa-c6c713c64331_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019f13c9-f5e5-7f36-bd4c-ebc699a20fb3" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_019f13c9-f5e5-748b-86fa-c6c713c64331" xlink:to="loc_srt_ProductsAndServicesDomain_019f13c9-f5e5-7f36-bd4c-ebc699a20fb3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_inhibrx_LicenseNonAffiliateMember_019f13c9-f5e5-7071-9394-067fd03c9085" xlink:href="inhibrx-20260630.xsd#inhibrx_LicenseNonAffiliateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019f13c9-f5e5-7f36-bd4c-ebc699a20fb3" xlink:to="loc_inhibrx_LicenseNonAffiliateMember_019f13c9-f5e5-7071-9394-067fd03c9085" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MajorCustomersAxis_019f13c9-f5e5-7e10-9481-9d30cc9e8c4e" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MajorCustomersAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable_019f13c9-f5e5-727f-ac65-32533b802d15" xlink:to="loc_srt_MajorCustomersAxis_019f13c9-f5e5-7e10-9481-9d30cc9e8c4e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_019f13c9-f5e5-7e10-9481-9d30cc9e8c4e_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_MajorCustomersAxis_019f13c9-f5e5-7e10-9481-9d30cc9e8c4e" xlink:to="loc_srt_NameOfMajorCustomerDomain_019f13c9-f5e5-7e10-9481-9d30cc9e8c4e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_019f13c9-f5e5-7e2e-959c-7a2740524f68" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_MajorCustomersAxis_019f13c9-f5e5-7e10-9481-9d30cc9e8c4e" xlink:to="loc_srt_NameOfMajorCustomerDomain_019f13c9-f5e5-7e2e-959c-7a2740524f68" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_inhibrx_ScitheraInc.Member_019f6417-7deb-7950-9ee2-44b17f91ef55" xlink:href="inhibrx-20260630.xsd#inhibrx_ScitheraInc.Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_019f13c9-f5e5-7e2e-959c-7a2740524f68" xlink:to="loc_inhibrx_ScitheraInc.Member_019f6417-7deb-7950-9ee2-44b17f91ef55" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_019f13c9-f5e5-7f49-9ca7-57d4c428a8a6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_019f13c9-f5e5-7874-bace-1d7d8784f387" xlink:to="loc_us-gaap_Revenues_019f13c9-f5e5-7f49-9ca7-57d4c428a8a6" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://inhibrx.namespace.com/role/LICENSEREVENUESNarrativeDetails" xlink:type="simple" xlink:href="inhibrx-20260630.xsd#LICENSEREVENUESNarrativeDetails"/>
  <link:definitionLink xlink:role="http://inhibrx.namespace.com/role/LICENSEREVENUESNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_019f13c9-f5e5-72dd-96f4-e8fdb3b9e757" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable_019f13c9-f5e5-7d17-bf3b-b40413b2b7b6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_019f13c9-f5e5-72dd-96f4-e8fdb3b9e757" xlink:to="loc_us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable_019f13c9-f5e5-7d17-bf3b-b40413b2b7b6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MajorCustomersAxis_019f641e-6907-73a3-93d8-d5cec1932abb" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MajorCustomersAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable_019f13c9-f5e5-7d17-bf3b-b40413b2b7b6" xlink:to="loc_srt_MajorCustomersAxis_019f641e-6907-73a3-93d8-d5cec1932abb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_019f641e-6907-73a3-93d8-d5cec1932abb_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_MajorCustomersAxis_019f641e-6907-73a3-93d8-d5cec1932abb" xlink:to="loc_srt_NameOfMajorCustomerDomain_019f641e-6907-73a3-93d8-d5cec1932abb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_019f641e-6907-73a1-9fe1-d5ec221e8452" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_MajorCustomersAxis_019f641e-6907-73a3-93d8-d5cec1932abb" xlink:to="loc_srt_NameOfMajorCustomerDomain_019f641e-6907-73a1-9fe1-d5ec221e8452" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_inhibrx_ScitheraInc.Member_019f641e-6907-7fee-8826-3ffbd681a96c" xlink:href="inhibrx-20260630.xsd#inhibrx_ScitheraInc.Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_019f641e-6907-73a1-9fe1-d5ec221e8452" xlink:to="loc_inhibrx_ScitheraInc.Member_019f641e-6907-7fee-8826-3ffbd681a96c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_019f641e-6907-7094-9d5c-33377e0adebe" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable_019f13c9-f5e5-7d17-bf3b-b40413b2b7b6" xlink:to="loc_srt_ProductOrServiceAxis_019f641e-6907-7094-9d5c-33377e0adebe" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019f641e-6907-7094-9d5c-33377e0adebe_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_019f641e-6907-7094-9d5c-33377e0adebe" xlink:to="loc_srt_ProductsAndServicesDomain_019f641e-6907-7094-9d5c-33377e0adebe_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019f641e-6907-75c8-8747-71ef0ca068d3" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_019f641e-6907-7094-9d5c-33377e0adebe" xlink:to="loc_srt_ProductsAndServicesDomain_019f641e-6907-75c8-8747-71ef0ca068d3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_inhibrx_LicenseNonAffiliateMember_019f641e-6907-757f-a83a-24c5c0456a09" xlink:href="inhibrx-20260630.xsd#inhibrx_LicenseNonAffiliateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019f641e-6907-75c8-8747-71ef0ca068d3" xlink:to="loc_inhibrx_LicenseNonAffiliateMember_019f641e-6907-757f-a83a-24c5c0456a09" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_inhibrx_CollaborativeArrangementNonrefundablePayment_019f13c9-f5e5-7a19-80d6-4fb9f216b50f" xlink:href="inhibrx-20260630.xsd#inhibrx_CollaborativeArrangementNonrefundablePayment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_019f13c9-f5e5-72dd-96f4-e8fdb3b9e757" xlink:to="loc_inhibrx_CollaborativeArrangementNonrefundablePayment_019f13c9-f5e5-7a19-80d6-4fb9f216b50f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_inhibrx_MaximumPotentialMilestonePayments_019f13c9-f5e5-7fba-9d5a-aa6db51037e1" xlink:href="inhibrx-20260630.xsd#inhibrx_MaximumPotentialMilestonePayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_019f13c9-f5e5-72dd-96f4-e8fdb3b9e757" xlink:to="loc_inhibrx_MaximumPotentialMilestonePayments_019f13c9-f5e5-7fba-9d5a-aa6db51037e1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_inhibrx_RevenueFromContractWithCustomerExcludingAssessedTaxNumberOfPerformanceObligation_019f13c9-f5e5-7b4b-952a-db5781b54e42" xlink:href="inhibrx-20260630.xsd#inhibrx_RevenueFromContractWithCustomerExcludingAssessedTaxNumberOfPerformanceObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_019f13c9-f5e5-72dd-96f4-e8fdb3b9e757" xlink:to="loc_inhibrx_RevenueFromContractWithCustomerExcludingAssessedTaxNumberOfPerformanceObligation_019f13c9-f5e5-7b4b-952a-db5781b54e42" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiabilityChangeInTimeframePerformanceObligationSatisfiedRevenueRecognized_019f641e-6907-7d99-a129-02c8c5110e6e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ContractWithCustomerLiabilityChangeInTimeframePerformanceObligationSatisfiedRevenueRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_019f13c9-f5e5-72dd-96f4-e8fdb3b9e757" xlink:to="loc_us-gaap_ContractWithCustomerLiabilityChangeInTimeframePerformanceObligationSatisfiedRevenueRecognized_019f641e-6907-7d99-a129-02c8c5110e6e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_019f13c9-f5e5-72a7-8e72-cc6300aefd6a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_019f13c9-f5e5-72dd-96f4-e8fdb3b9e757" xlink:to="loc_us-gaap_Revenues_019f13c9-f5e5-72a7-8e72-cc6300aefd6a" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://inhibrx.namespace.com/role/SUBSEQUENTEVENTSDetails" xlink:type="simple" xlink:href="inhibrx-20260630.xsd#SUBSEQUENTEVENTSDetails"/>
  <link:definitionLink xlink:role="http://inhibrx.namespace.com/role/SUBSEQUENTEVENTSDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventLineItems_019f13c9-f5e5-7a5e-83a3-698c3835442e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTable_019f13c9-f5e5-7440-8139-9acd43f7fc3a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SubsequentEventLineItems_019f13c9-f5e5-7a5e-83a3-698c3835442e" xlink:to="loc_us-gaap_SubsequentEventTable_019f13c9-f5e5-7440-8139-9acd43f7fc3a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_019f13c9-f5e5-7d12-8ed1-6e28bc3dd2f7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_019f13c9-f5e5-7440-8139-9acd43f7fc3a" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_019f13c9-f5e5-7d12-8ed1-6e28bc3dd2f7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019f13c9-f5e5-7d12-8ed1-6e28bc3dd2f7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_019f13c9-f5e5-7d12-8ed1-6e28bc3dd2f7" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019f13c9-f5e5-7d12-8ed1-6e28bc3dd2f7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019f13c9-f5e5-7298-8449-f0eec0dd4c8f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_019f13c9-f5e5-7d12-8ed1-6e28bc3dd2f7" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019f13c9-f5e5-7298-8449-f0eec0dd4c8f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_019f13c9-f5e5-7ae5-bd89-21408447ab8a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_019f13c9-f5e5-7298-8449-f0eec0dd4c8f" xlink:to="loc_us-gaap_SubsequentEventMember_019f13c9-f5e5-7ae5-bd89-21408447ab8a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_019f6432-def2-7dfe-ae7f-daa6b68f784b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_019f13c9-f5e5-7440-8139-9acd43f7fc3a" xlink:to="loc_us-gaap_CreditFacilityAxis_019f6432-def2-7dfe-ae7f-daa6b68f784b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019f6432-def2-7dfe-ae7f-daa6b68f784b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_019f6432-def2-7dfe-ae7f-daa6b68f784b" xlink:to="loc_us-gaap_CreditFacilityDomain_019f6432-def2-7dfe-ae7f-daa6b68f784b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019f6432-def2-7f32-95e6-9634c74a4607" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_019f6432-def2-7dfe-ae7f-daa6b68f784b" xlink:to="loc_us-gaap_CreditFacilityDomain_019f6432-def2-7f32-95e6-9634c74a4607" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebtMember_019f6432-def2-73cf-97ec-551946eaa0dc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019f6432-def2-7f32-95e6-9634c74a4607" xlink:to="loc_us-gaap_SecuredDebtMember_019f6432-def2-73cf-97ec-551946eaa0dc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019f6432-def2-7359-8c72-52ba396cf5c2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_019f13c9-f5e5-7440-8139-9acd43f7fc3a" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019f6432-def2-7359-8c72-52ba396cf5c2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019f6432-def2-7359-8c72-52ba396cf5c2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019f6432-def2-7359-8c72-52ba396cf5c2" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019f6432-def2-7359-8c72-52ba396cf5c2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019f6432-def2-7a81-99ac-e817987ad3af" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019f6432-def2-7359-8c72-52ba396cf5c2" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019f6432-def2-7a81-99ac-e817987ad3af" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_019f6432-def2-7bf6-befd-dd3ace43670f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f6432-def2-7a81-99ac-e817987ad3af" xlink:to="loc_us-gaap_LineOfCreditMember_019f6432-def2-7bf6-befd-dd3ace43670f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfLongTermDebt_019f6432-def2-7841-b280-80bda74722bd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromIssuanceOfLongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_019f13c9-f5e5-7a5e-83a3-698c3835442e" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfLongTermDebt_019f6432-def2-7841-b280-80bda74722bd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_inhibrx_LineOfCreditFacilityMaximumBorrowingCapacityFundedUponExecutionOfTheAmendment_019f6432-def2-7731-9c92-66c7def01914" xlink:href="inhibrx-20260630.xsd#inhibrx_LineOfCreditFacilityMaximumBorrowingCapacityFundedUponExecutionOfTheAmendment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_019f13c9-f5e5-7a5e-83a3-698c3835442e" xlink:to="loc_inhibrx_LineOfCreditFacilityMaximumBorrowingCapacityFundedUponExecutionOfTheAmendment_019f6432-def2-7731-9c92-66c7def01914" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_inhibrx_LineOfCreditFacilityMaximumBorrowingCapacityAdditionalFunds_019f6432-def2-76f9-808b-a6b8f6b1c9a9" xlink:href="inhibrx-20260630.xsd#inhibrx_LineOfCreditFacilityMaximumBorrowingCapacityAdditionalFunds"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_019f13c9-f5e5-7a5e-83a3-698c3835442e" xlink:to="loc_inhibrx_LineOfCreditFacilityMaximumBorrowingCapacityAdditionalFunds_019f6432-def2-76f9-808b-a6b8f6b1c9a9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_inhibrx_LineOfCreditFacilityMaximumBorrowingCapacityAccordionFeature_019f6432-def2-7ca9-b918-d2fa8d2a67f2" xlink:href="inhibrx-20260630.xsd#inhibrx_LineOfCreditFacilityMaximumBorrowingCapacityAccordionFeature"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_019f13c9-f5e5-7a5e-83a3-698c3835442e" xlink:to="loc_inhibrx_LineOfCreditFacilityMaximumBorrowingCapacityAccordionFeature_019f6432-def2-7ca9-b918-d2fa8d2a67f2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights_019f6431-276c-7f1b-a7ac-00a93106ab6f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_019f13c9-f5e5-7a5e-83a3-698c3835442e" xlink:to="loc_us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights_019f6431-276c-7f1b-a7ac-00a93106ab6f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockParOrStatedValuePerShare_019f6431-f908-7ced-bc41-7dd8c5a7e70f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockParOrStatedValuePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_019f13c9-f5e5-7a5e-83a3-698c3835442e" xlink:to="loc_us-gaap_CommonStockParOrStatedValuePerShare_019f6431-f908-7ced-bc41-7dd8c5a7e70f" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_019f6431-90df-75b5-98df-484c611ba215" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_019f13c9-f5e5-7a5e-83a3-698c3835442e" xlink:to="loc_us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_019f6431-90df-75b5-98df-484c611ba215" xlink:type="arc" order="6"/>
  </link:definitionLink>
</link:linkbase>
