UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 14A

Proxy Statement Pursuant to Section 14(a) of
the Securities Exchange Act of 1934 (Amendment No.       )

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Preliminary Proxy Statement

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Definitive Proxy Statement

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Definitive Additional Materials

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Soliciting Material under §240.14a-12

Albireo Pharma, Inc.

(Name of Registrant as Specified In Its Charter)

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

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 Your Vote Counts! ALBIREO PHARMA, INC. 2021 Annual Meeting Vote by June 16, 2021 11:59 PM ET 10 POST OFFICE SQ., SUITE 1000 BOSTON, MA 02109 D49447-P51727 You invested in ALBIREO PHARMA, INC. and it’s time to vote! You have the right to vote on proposals being presented at the Annual Meeting. This is an important notice regarding the availability of proxy material for the stockholder meeting to be held on June 17, 2021. Get informed before you vote View the Notice and Proxy Statement and Annual Report online OR you can receive a free paper or email copy of the material(s) by requesting prior to June 3, 2021. If you would like to request a copy of the material(s) for this and/or future stockholder meetings, you may (1) visit www.ProxyVote.com, (2) call 1-800-579-1639 or (3) send an email to sendmaterial@proxyvote.com. If sending an email, please include your control number (indicated below) in the subject line. Unless requested, you will not otherwise receive a paper or email copy. For complete information and to vote, visit www.ProxyVote.com Control # Smartphone users Point your camera here and vote without entering a control number Virtually at: Vote Virtually at the Meeting* June 17, 2021 8:30 AM ET www.virtualshareholdermeeting.com/ALBO2021 *Please check the meeting materials for any special requirements for meeting attendance. V1

Vote at www.ProxyVote.com THIS IS NOT A VOTABLE BALLOT This is an overview of the proposals being presented at the upcoming stockholder meeting. Please follow the instructions on the reverse side to vote these important matters. Voting Items To elect three Class II directors to serve three-year terms expiring in 2024: Nominees: Ronald H.W. Cooper Anne Klibanski, M.D. Stephanie S. Okey, M.S. To approve an amendment to Albireo’s Restated Certificate of Incorporation, as amended, to increase the number of shares of common stock authorized for issuance from 30,000,000 to 60,000,000. To approve the amendment to the Albireo Pharma, Inc. 2018 Equity Incentive Plan, as amended. To ratify the appointment of Ernst & Young LLP as Albireo’s independent registered public accounting firm for the fiscal year ending December 31, 2021. NOTE: Such other business as may properly come before the meeting or any adjournment or postponement thereof. Board Recommends For For For For Prefer to receive an email instead? While voting on www.ProxyVote.com, be sure to click “Sign up for E-delivery”. D49448-P51727