The First Bancshares, Inc. (FBMS) DEFA14AAdditional proxy soliciting materials

www.investorvote.com/FBMS Step 1: Go to www.investorvote.com/FBMS. Step 2: Click on the icon on the right to view meeting materials. Step 3: Return to the investorvote.com window and follow the instructions on the screen to log in. Online Go to www.investorvote.com/FBMS or scan the QR code — login details are located in the shaded bar below. Shareholder Meeting Notice 03Z90B + + Important Notice Regarding the Availability of Proxy Materials for The First Bancshares, Inc. Shareholder Meeting to be Held on May 23, 2024 Under Securities and Exchange Commission rules, you are receiving this notice that the proxy materials for the annual shareholders’ meeting are available on the Internet. Follow the instructions below to view the materials and vote online or request a copy. The items to be voted on and location of the annual meeting are on the reverse side. Your vote is important! This communication presents only an overview of the more complete proxy materials that are available to you on the Internet. We encourage you to access and review all of the important information contained in the proxy materials before voting. The 2024 Proxy Statement and 2023 Annual Report to shareholders are available at: Obtaining a Copy of the Proxy Materials – If you want to receive a copy of the proxy materials, you must request one. There is no charge to you for requesting a copy. Please make your request as instructed on the reverse side on or before May 13, 2024 to facilitate timely delivery. 2NOT Easy Online Access — View your proxy materials and vote. When you go online, you can also help the environment by consenting to receive electronic delivery of future materials. Step 4: Make your selections as instructed on each screen for your delivery preferences. Step 5: Vote your shares.

Here’s how to order a copy of the proxy materials and select delivery preferences: Current and future delivery requests can be submitted using the options below. If you request an email copy, you will receive an email with a link to the current meeting materials. PLEASE NOTE: You must use the number in the shaded bar on the reverse side when requesting a copy of the proxy materials. — Internet – Go to www.investorvote.com/FBMS. — Phone – Call us free of charge at 1-866-641-4276. — Email – Send an email to investorvote@computershare.com with “Proxy Materials The First Bancshares, Inc.” in the subject line. Include your full name and address, plus the number located in the shaded bar on the reverse side, and state that you want a paper copy of the meeting materials. To facilitate timely delivery, requests for a paper copy of proxy materials must be received by May 13, 2024. The First Bancshares, Inc.’s Annual Meeting of Shareholders will be held on May 23, 2024 at 2:00 P.M. Central Time, virtually via the internet at https://meetnow.global/MNA5TCA. To access the virtual meeting, you must have the information that is printed in the shaded bar located on the reverse side of this form. Proposals to be voted on at the meeting are listed below along with the Board of Directors’ recommendations. The Board Directors recommends a vote FOR all nominees, FOR Proposals 2, 3 and 4. 1. Election of Directors: 01 - David W. Bomboy 02 - M. Ray “Hoppy” Cole, Jr. 03 - E. Ricky Gibson 04 - Jonathan A. Levy 05 - Charles R. Lightsey 06 - Fred A. McMurry 07 - Thomas E. Mitchell 08 - Renee Moore 09 - Ted E. Parker 10 - J. Douglas Seidenburg 11 - Andrew D. Stetelman 12 - Valencia M. Williamson 2. Approval, on an advisory basis, of the compensation of our named executive officers 3. Approval of an amendment to the 2007 Stock Incentive Plan 4. Ratification of the appointment of FORVIS, LLP as the independent registered public accounting firm of the Company for the fiscal year 2024 PLEASE NOTE – YOU CANNOT VOTE BY RETURNING THIS NOTICE. To vote your shares you must go online or request a paper copy of the proxy materials to receive a proxy card. Shareholder Meeting Notice