Riot Platforms Inc

APPENDIX A

ANNUAL GENERAL MEETING OF STOCKHOLDERS JUNE 12, 2024

PROXY SOLICITED ON BEHALF OF THE BOARD OF DIRECTORS

By completing, executing, and submitting the attached Proxy Card, the stockholder of Riot Platforms, Inc. (the “Company”) constitutes and appoints the Chief Executive Officer of the Company, Mr. Jason Les, as the stockholder’s Attorney and Proxy to appear, attend and vote all of the shares of common stock the stockholder is entitled to vote at the 2024 Annual General Meeting of the stockholders of the Company, to be held in a virtual-only format atwww.virtualstockholdermeeting.com/RIOT2024 on Wednesday, June 12, 2024, beginning at 10:00 a.m. (Eastern Time), and at any adjournments or postponements thereof (the “Annual Meeting”). Such shares shall be voted as indicated with respect to the proposals listed on the Proxy Card and in the discretion of the Proxy on such other matters as may properly come before the Annual Meeting or any adjournments or postponements thereof in accordance with and as described in the Notice of the 2024 Annual General Meeting of Stockholders and Proxy Statement, which are available online atwww.proxyvote.com and on our website atwww.RiotPlatforms.com.

Before the Annual Meeting, please either submit your Proxy Card via the Internet atwww.proxyvote.comby using the 16-digit control number assigned to you on your Proxy Card, by telephone by dialing 1-800-690-6903, or by mail. If you wish to submit your Proxy Card by mail, please complete, date and sign exactly as your name appears on your Proxy Card, including any designation as executor, Trustee, etc., if applicable, and return the Proxy Card in the enclosed pre-addressed, postage-paid envelope as promptly as possible to: Vote Processing, c/o Broadridge, 51 Mercedes Way, Edgewood, NY 11717.

It is important to return the Proxy Card properly executed in order to exercise your right to vote if you do not attend the Annual Meeting and vote live and online during the virtual webcast. The Proxy Card must be signed by a corporation or other entity’s authorized officer to be effective. All co-owners and each joint owner must sign and date the Proxy Card.

The 2024 Proxy Card is attached on the following page