<?xml version="1.0" encoding="UTF-8"?>
<edgarSubmission xmlns:com="http://www.sec.gov/edgar/common" xmlns="http://www.sec.gov/edgar/thirteenffiler">
  <schemaVersion>X0202</schemaVersion>
  <headerData>
    <submissionType>13F-HR</submissionType>
    <filerInfo>
      <liveTestFlag>LIVE</liveTestFlag>
      <filer>
        <credentials>
          <cik>0000916542</cik>
          <ccc>XXXXXXXX</ccc>
        </credentials>
      </filer>
      <periodOfReport>09-30-2025</periodOfReport>
    </filerInfo>
  </headerData>
  <formData>
    <coverPage>
      <reportCalendarOrQuarter>09-30-2025</reportCalendarOrQuarter>
      <isAmendment>false</isAmendment>
      <filingManager>
        <name>ACADIAN ASSET MANAGEMENT LLC</name>
        <address>
          <com:street1>260 Franklin Street</com:street1>
          <com:city>Boston</com:city>
          <com:stateOrCountry>MA</com:stateOrCountry>
          <com:zipCode>02110</com:zipCode>
        </address>
      </filingManager>
      <reportType>13F COMBINATION REPORT</reportType>
      <form13FFileNumber>028-05990</form13FFileNumber>
      <otherManagersInfo>
        <otherManager>
          <cik>0000721204</cik>
          <form13FFileNumber>028-01190</form13FFileNumber>
          <name>RUSSELL FRANK CO/</name>
        </otherManager>
      </otherManagersInfo>
      <provideInfoForInstruction5>N</provideInfoForInstruction5>
    </coverPage>
    <signatureBlock>
      <name>Alison Peabody</name>
      <title>VP, Compliance Officer</title>
      <phone>(617) 850-3500</phone>
      <signature>/s/ Alison Peabody</signature>
      <city>Boston</city>
      <stateOrCountry>MA</stateOrCountry>
      <signatureDate>11-10-2025</signatureDate>
    </signatureBlock>
    <summaryPage>
      <otherIncludedManagersCount>1</otherIncludedManagersCount>
      <tableEntryTotal>1819</tableEntryTotal>
      <tableValueTotal>57295628</tableValueTotal>
      <otherManagers2Info>
        <otherManager2>
          <sequenceNumber>1</sequenceNumber>
          <otherManager>
            <cik>0000796370</cik>
            <form13FFileNumber>028-11931</form13FFileNumber>
            <name>Acadian Inc</name>
          </otherManager>
        </otherManager2>
      </otherManagers2Info>
    </summaryPage>
  </formData>
</edgarSubmission>
