<?xml version="1.0" encoding="UTF-8"?><edgarSubmission xmlns="http://www.sec.gov/edgar/ownership" xmlns:com="http://www.sec.gov/edgar/common">
  <headerData>
    <submissionType>144</submissionType>
    <filerInfo>
      <filer>
        <filerCredentials>
          <cik>0001629278</cik>
          <ccc>XXXXXXXX</ccc>
        </filerCredentials>
      </filer>
      <liveTestFlag>LIVE</liveTestFlag>



    </filerInfo>
  </headerData>
  <formData>
    <issuerInfo>
      <issuerCik>0001293971</issuerCik>
      <issuerName>bluebird bio, Inc.</issuerName>
      <secFileNumber>001-35966</secFileNumber>
      <issuerAddress>
        <com:street1>455 Grand Union Boulevard</com:street1>
        <com:city>Somerville</com:city>
        <com:stateOrCountry>MA</com:stateOrCountry>
        <com:zipCode>02145</com:zipCode>
      </issuerAddress>
      <issuerContactPhone>3394999300</issuerContactPhone>
      <nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>Klima Thomas J</nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>
      <relationshipsToIssuer>
        <relationshipToIssuer>Officer</relationshipToIssuer>
      </relationshipsToIssuer>
    </issuerInfo>
    <securitiesInformation>
      <securitiesClassTitle>Common Stock</securitiesClassTitle>
      <brokerOrMarketmakerDetails>
        <name>Morgan Stanley</name>
        <address>
          <com:street1>1500 - 600 3 Ave SW</com:street1>
          <com:city>Calgary</com:city>
          <com:stateOrCountry>A0</com:stateOrCountry>
          <com:zipCode>T2P 0G5</com:zipCode>
        </address>
      </brokerOrMarketmakerDetails>
      <noOfUnitsSold>500</noOfUnitsSold>
      <aggregateMarketValue>1956.67</aggregateMarketValue>
      <noOfUnitsOutstanding>9740894</noOfUnitsOutstanding>
      <approxSaleDate>03/03/2025</approxSaleDate>
      <securitiesExchangeName>NASDAQ</securitiesExchangeName>
    </securitiesInformation>
    <securitiesToBeSold>
      <securitiesClassTitle>Common</securitiesClassTitle>
      <acquiredDate>03/01/2023</acquiredDate>
      <natureOfAcquisitionTransaction>Vested restricted stock units under company equity plan; sale of shares due to withholding taxes</natureOfAcquisitionTransaction>
      <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
      <isGiftTransaction>N</isGiftTransaction>
      <amountOfSecuritiesAcquired>688</amountOfSecuritiesAcquired>
      <paymentDate>03/03/2025</paymentDate>
      <natureOfPayment>Services rendered</natureOfPayment>
    </securitiesToBeSold>
    <securitiesToBeSold>
      <securitiesClassTitle>Common</securitiesClassTitle>
      <acquiredDate>09/30/2024</acquiredDate>
      <natureOfAcquisitionTransaction>Vested restricted stock units under company equity plan; sale of shares due to withholding taxes</natureOfAcquisitionTransaction>
      <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
      <isGiftTransaction>N</isGiftTransaction>
      <amountOfSecuritiesAcquired>625</amountOfSecuritiesAcquired>
      <paymentDate>03/03/2025</paymentDate>
      <natureOfPayment>Services rendered</natureOfPayment>
    </securitiesToBeSold>
    <nothingToReportFlagOnSecuritiesSoldInPast3Months>N</nothingToReportFlagOnSecuritiesSoldInPast3Months>
    <securitiesSoldInPast3Months>
      <sellerDetails>
        <name>Thomas J. Klima</name>
        <address>
          <com:street1>c/o bluebird bio, Inc.</com:street1>
          <com:street2>455 Grand Union Boulevard</com:street2>
          <com:city>Somerville</com:city>
          <com:stateOrCountry>MA</com:stateOrCountry>
          <com:zipCode>02145</com:zipCode>
        </address>
      </sellerDetails>
      <securitiesClassTitle>Common</securitiesClassTitle>
      <saleDate>02/03/2025</saleDate>
      <amountOfSecuritiesSold>122</amountOfSecuritiesSold>
      <grossProceeds>901.89</grossProceeds>
    </securitiesSoldInPast3Months>
    <remarks>Shares to be sold to cover withholding taxes upon vesting of restricted stock unit awards pursuant to standing Rule 10b5-1 sell to cover instruction.
Exhibit List: Exhibit 24 - Power of Attorney</remarks>
    <noticeSignature>
      <noticeDate>03/03/2025</noticeDate>
      <planAdoptionDates>
        <planAdoptionDate>05/10/2023</planAdoptionDate>
      </planAdoptionDates>
      <signature>/s/ Sydney Gaylin, attorney-in-fact for Thomas J. Klima</signature>
    </noticeSignature>
  </formData>

</edgarSubmission>
[{"type": "144", "sequence": "1", "filename": "primary_doc.xml", "secsgml_size_bytes": 4416}]
144
0001629278
XXXXXXXX
LIVE
0001293971
bluebird bio, Inc.
001-35966
455 Grand Union Boulevard
Somerville
MA
02145
3394999300
Klima Thomas J
Officer
Common Stock
Morgan Stanley
1500 - 600 3 Ave SW
Calgary
A0
T2P 0G5
500
1956.67
9740894
03/03/2025
NASDAQ
Common
03/01/2023
Vested restricted stock units under company equity plan; sale of shares due to withholding taxes
Issuer
N
688
03/03/2025
Services rendered
Common
09/30/2024
Vested restricted stock units under company equity plan; sale of shares due to withholding taxes
Issuer
N
625
03/03/2025
Services rendered
N
Thomas J. Klima
c/o bluebird bio, Inc.
455 Grand Union Boulevard
Somerville
MA
02145
Common
02/03/2025
122
901.89
Shares to be sold to cover withholding taxes upon vesting of restricted stock unit awards pursuant to standing Rule 10b5-1 sell to cover instruction.
Exhibit List: Exhibit 24 - Power of Attorney
03/03/2025
05/10/2023
/s/ Sydney Gaylin, attorney-in-fact for Thomas J. Klima