EX-99.1

Exhibit 99.1

LOGO

COLUMBIA FINANCIAL, INC. C/O BROADRIDGE CORPORATE ISSUER SOLUTIONS P.O. BOX 1342 BRENTWOOD, NY 11717 SCAN TO VIEW MATERIALS & VOTE w VOTE BY INTERNET Before The Meeting - Go to www.proxyvote.com or scan the QR Barcode above Use the Internet to transmit your voting instructions and for electronic delivery of information. Vote by 11:59 p.m. Eastern Time on June 24, 2026 for shares held directly and by 11:59 p.m. Eastern Time on June 18, 2026 for shares held in a Plan. Have your proxy card in hand when you access the web site and follow the instructions to obtain your records and to create an electronic voting instruction form. During The Meeting - Go to www.virtualshareholdermeeting.com/CLBK2026 You may attend the meeting via the Internet and vote during the meeting. Have the information that is printed in the box marked by the arrow available and follow the instructions. VOTE BY PHONE—1-800-690-6903 Use any touch-tone telephone to transmit your voting instructions. Vote by 11:59 p.m. Eastern Time on June 24, 2026 for shares held directly and by 11:59 p.m. Eastern Time on June 18, 2026 for shares held in a Plan. Have your proxy card in hand when you call and then follow the instructions. VOTE BY MAIL Mark, sign and date your proxy card and return it in the postage-paid envelope we have provided or return it to Vote Processing, c/o Broadridge, 51 Mercedes Way, Edgewood, NY 11717. TO VOTE, MARK BLOCKS BELOW IN BLUE OR BLACK INK AS FOLLOWS: V95890-P52843 KEEP THIS PORTION FOR YOUR RECORDS THIS PROXY CARD IS VALID ONLY WHEN SIGNED AND DATED. DETACH AND RETURN THIS PORTION ONLY COLUMBIA FINANCIAL, INC. The Board of Directors recommends that you vote FOR Proposals 1, 2, 3, 4, 6, 7 and 9, FOR each of the director nominees set forth in For Against Abstain Proposal 5 and for ONE YEAR with respect to Proposal 8. 1. The approval of the Plan of Conversion and Reorganization ! ! ! 2. The approval of the Agreement and Plan of Merger, dated as of January 31, 2026, by and among Columbia Financial, Inc. ! ! ! For Against Abstain (a Delaware corporation), Columbia Financial, Inc. (a Maryland corporation), Columbia Bank MHC and Northfield Bancorp, Inc. 6. The ratification of the appointment of KPMG LLP as independent and the transactions contemplated thereby, including the issuance registered public accounting firm for the fiscal year ending ! ! ! of shares of Columbia Financial, Inc. common stock as merger December 31, 2026 consideration 7. The approval, on an advisory (non-binding) basis, of the ! ! ! compensation of Columbia Financial’s named executive officers 3. The approval of an informational proposal regarding approval of a provision in Columbia Financial, Inc.’s articles of incorporation ! ! ! 1 Year 2 Years 3 Years Abstain requiring a super-majority vote to approve certain amendments to Columbia Financial, Inc.’s articles of incorporation 8. frequency The approval, of the on vote an advisory on the compensation (non-binding) of basis, Columbia of the ! ! ! ! 4. The approval of an informational proposal regarding approval of Financial’s named executive officers a provision in Columbia Financial, Inc.’s articles of incorporation ! ! ! For Against Abstain to limit the voting rights of shares beneficially owned in excess of 10% of Columbia Financial, Inc.’s outstanding voting stock 5. The election of directors to a three-year term: For Against Withhold 9. The approval of the adjournment of the annual meeting, if ! ! ! necessary, to solicit additional proxies 5a. Dennis E. Gibney ! ! ! 5b. Robert Van Dyk ! ! ! 5c. James H. Wainwright ! ! ! Please sign exactly as your name(s) appear(s) hereon. When signing as attorney, executor, administrator, or other fiduciary, please give full title as such. Joint owners should each sign personally. All holders must sign. If a corporation or partnership, please sign in full corporate or partnership name by authorized officer. Signature [PLEASE SIGN WITHIN BOX] Date Signature (Joint Owners) Date