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| Signature of Stockholder Date: Signature of Stockholder Date: Note:Please sign exactly as your name or names appear on this Proxy. When shares are held jointly, each holder should sign. When signing as executor, administrator, attorney, trustee or guardian, please give full title as such. If the signer is a corporation, please sign full corporate name by duly authorized officer, giving full title as such. If signer is a partnership, please sign in partnership name by authorized person. To change the address on your account, please check the box at right and indicate your new address in the address space above. Please note that changes to the registered name(s) on the account may not be submitted via this method. JOHN SMITH 1234 MAIN STREET APT. 203 NEW YORK, NY 10038 INTERNET- Access “ www.voteproxy.com ” and follow the on-screen instructions or scan the QR code with your smartphone. Have your proxy card available when you access the web page. TELEPHONE- Call toll-free 1-800-PROXIES (1-800-776-9437) in the United States or 1-718-921-8500 from foreign countries from any touch-tone telephone and follow the instructions. Have your proxy card available when you call. Vote online/phone until 11:59 PM ET on [ ], 2022. MAIL- Sign, date and mail your proxy card in the envelope provided as soon as possible. IN PERSON- You may vote your shares in person by attending the Special Meeting. GO GREEN- e-Consent makes it easy to go paperless. With e-Consent, you can quickly access your proxy material, statements and other eligible documents online, while reducing costs, clutter and paper waste. Enroll today via www.astfinancial.com to enjoy online access. PROXY VOTING INSTRUCTIONS Please detach along perforated line and mail in the envelope provided IF you are not voting via telephone or the Internet. THE BOARD OF DIRECTORS UNANIMOUSLY RECOMMENDS A VOTE "FOR" PROPOSALS 1, 2 AND 3. PLEASE SIGN, DATE AND RETURN PROMPTLY IN THE ENCLOSED ENVELOPE. PLEASE MARK YOUR VOTE IN BLUE OR BLACK INK AS SHOWN HERE x 00030300300000000000 5 000022 COMPANY NUMBER ACCOUNT NUMBER SPECIAL MEETING OF STOCKHOLDERS OF PCSB FINANCIAL CORPORATION [ ], 2022 1. To approve the Agreement and Plan of Merger dated as of May 23, 2022, by and between Brookline Bancorp, Inc. and PCSB Financial Corporation, and the transactions contemplated by it. 2. To approve, on a non-binding, advisory basis, the compensation payable to the named executive officers of PCSB Financial Corporation in connection with the merger of PCSB Financial Corporation with and into Brookline Bancorp, Inc. 3. To approve the adjournment of the Special Meeting, if necessary, to permit further solicitation of proxies. FORAGAINSTABSTAIN |