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. 1)

Filed by the Registrant  ☒                Filed by a Party other than the Registrant  ☐

Check the appropriate box:

☐ Preliminary Proxy Statement

☐ Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2))

☒ Definitive Proxy Statement

☐ Definitive Additional Materials

☐ Soliciting Material Pursuant to §240.14a-12

BLACKSTONE MORTGAGE TRUST, INC.

(Name of Registrant as Specified In Its Charter)

(Name of Person(s) Filing Proxy Statement, if Other Than the Registrant)

Payment of Filing Fee (Check all boxes that apply):

☒ No fee required

☐ Fee paid previously with preliminary materials

☐ Fee computed on table in exhibit required by Item 25(b) per Exchange Act Rules 14a-6(i)(1) and 0-11

Explanatory Note

This Amendment No. 1 to Schedule 14A (this “Amendment”) is being filed solely to amend and replace the sample proxy card included in the Definitive Proxy Statement filed by Blackstone Mortgage Trust, Inc. (the “Company”) with the Securities and Exchange Commission on April 27, 2023 (the “Proxy Statement”) in order to conform the list of director nominees to those listed in the body of the Proxy Statement. No changes have been made to the body of the Proxy Statement and an updated proxy card has been included in the Proxy Statement being mailed to the Company’s stockholders. This Amendment applies only to the version of the sample proxy card originally filed with the Proxy Statement.

BLACKSTONE MORTGAGE TRUST, INC. 24TH FLOOR, 345 PARK AVENUE NEW YORK, NY 10154 SCAN TO VIEW MATERIALS & VOTE 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 up until 11:59 p.m. Eastern Time on June 22, 2023. 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/BXMT2023 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 up until 11:59 p.m. Eastern Time on June 22, 2023. 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. Mailed proxy cards must be received by 11:59 p.m. Eastern Time on June 22, 2023. TO VOTE, MARK BLOCKS BELOW IN BLUE OR BLACK INK AS FOLLOWS: V17767-P89098 KEEP THIS PORTION FOR YOUR RECORDS THIS PROXY CARD IS VALID ONLY WHEN SIGNED AND DATED. DETACH AND RETURN THIS PORTION ONLY BLACKSTONE MORTGAGE TRUST, INC. For All Withhold All For All Except To withhold authority to vote for any individual nominee(s), mark “For All Except” and write the number(s) of the nominee(s) on the line below. The Board of Directors recommends you vote FOR the following: 1. Election Of Directors Nominees: 01) Michael B. Nash 02) Katharine A. Keenan 03) Leonard W. Cotton 04) Thomas E. Dobrowski 05) Timothy Johnson 06) Nnenna Lynch 07) Henry N. Nassau 08) Gilda Perez-Alvarado 09) Jonathan L. Pollack 10) Lynne B. Sagalyn The Board of Directors recommends you vote FOR proposals 2 and 3 2. Ratify the appointment of Deloitte & Touche LLP as the Company’s independent registered public accounting firm for the fiscal year ending December 31, 2023. 3. Advisory Vote on Executive Compensation: To approve in a non-binding, advisory vote, the compensation paid to our named executive officers. For Against Abstain Note: To consider and act upon any other matters which may properly come before the meeting or any adjournment or postponement thereof. 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

Important Notice Regarding the Availability of Proxy Materials for the Annual Meeting: The Notice and Proxy Statement and Annual Report are available at www.proxyvote.com. V17768-P89098 Annual Meeting of Blackstone Mortgage Trust, Inc.to be held on Friday, June 23, 2023 for Holders as of April 14, 2023 This proxy is being solicited on behalf of the Board of Directors The undersigned stockholder(s) hereby appoint(s) Katharine A. Keenan, Anthony F. Marone, Jr. and Leon Volchyok, or any of them, as proxies for the undersigned, each with the full power to appoint his/her substitute, and hereby authorize(s) them to represent the undersigned and to vote, as designated on the reverse side of this proxy card, all of the shares of Class A Common Stock of BLACKSTONE MORTGAGE TRUST, INC., a Maryland corporation, that the stockholder(s) is/are entitled to vote at the Annual Meeting of Stockholders to be held at 9:00 AM Eastern Time on June 23, 2023 at www.virtualshareholdermeeting.com/BXMT2023, and any adjournment or postponement thereof and further authorize(s) such proxies to vote such shares in their discretion upon such other business as may properly come before the Annual Meeting of Stockholders and any adjournment or postponement thereof. The undersigned hereby acknowledges receipt of the Notice of the Annual Meeting of Stockholders and of the accompanying Proxy Statement and revokes any proxy heretofore given with respect to such meeting and any adjournments or postponements thereof. THE SHARES REPRESENTED BY THIS PROXY WILL BE VOTED AS DIRECTED OR, IF NO DIRECTION IS GIVEN, SHARES WILL BE VOTED “FOR” THE ELECTION OF THE DIRECTORS IN ITEM 1, AND “FOR” THE PROPOSALS IN ITEMS 2 AND 3. SUCH SHARES WILL BE VOTED IN THE DISCRETION OF THE PROXIES UPON SUCH OTHER MATTERS AS MAY PROPERLY COME BEFORE THE ANNUAL MEETING. Continued and to be signed on reverse side