Fluence Energy, Inc.

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

(Rule 14a-101)

INFORMATION REQUIRED IN PROXY STATEMENT

SCHEDULE 14A INFORMATION

PROXY STATEMENT PURSUANT TO SECTION 14(a) OF THE

SECURITIES EXCHANGE ACT OF 1934

(AMENDMENT NO. )

Check the appropriate box:

(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):

January 26, 2026

To our Stockholders:

On behalf of the Board of Directors, I cordially invite you to attend the 2026 annual meeting of stockholders (the “Annual Meeting”) of Fluence Energy, Inc., which will be held on Thursday, March 12, 2026, beginning at 10:00 a.m. Eastern Time. The Annual Meeting will be a completely virtual meeting that will be conducted via live webcast.

In accordance with the U.S. Securities and Exchange Commission rules allowing companies to furnish proxy materials to their stockholders over the Internet, we have sent holders of record of our common stock (composed of Class A common stock, Class B-1 common stock, and Class B-2 common stock) at the close of business on Friday, January 13, 2026 a Notice of Internet Availability of Proxy Materials. Stockholders will not receive paper copies of the proxy materials unless they request them.

Attached to this letter are a Notice of Annual Meeting of Stockholders and Proxy Statement, which describe the business to be conducted at the Annual Meeting. The Notice contains instructions on how to access our Proxy Statement and Annual Report and vote online. If you would like to receive a printed copy of our proxy materials from us instead of downloading a printable version from the Internet, please follow the instructions for requesting such materials included in the Notice, as well as in the attached Proxy Statement.

Your vote is important regardless of the number of shares that you hold. Please act as soon as possible to vote your shares. It is important that your shares be represented at the meeting whether or not you plan to attend the Annual Meeting via the Internet. Please vote electronically over the Internet, by telephone or, if you receive a paper copy of the proxy card by mail, by returning your signed proxy card in the envelope provided. You also may vote your shares online during the Annual Meeting. Instructions on how to vote while participating at the meeting live via the Internet are posted atwww.virtualshareholdermeeting.com/FLNC2026.

On behalf of the Fluence Board of Directors and management, it is my pleasure to express our sincere appreciation for your continued support.

Herman BullsChairperson of the Board of Directors

NOTICE OF ANNUAL MEETING OF STOCKHOLDERS

NOTICE IS HEREBY GIVEN that the Annual Meeting of Stockholders (the “Annual Meeting”) of Fluence Energy, Inc., a Delaware corporation (the “Company”), will be held on March 12, 2026, at 10:00 a.m., Eastern Time. The Annual Meeting will be a completely virtual meeting, which will be conducted via live webcast. You will be able to attend the Annual Meeting online and submit your questions during the meeting by visitingwww.virtualshareholdermeeting.com/FLNC2026. For instructions on how to attend and vote your shares at the Annual Meeting, see the information in the accompanying Proxy Statement in the section titled “Questions and Answers About the Annual Meeting, Proxy Materials, and Voting — How can I attend and vote at the Annual Meeting?”

The Annual Meeting is being held:

These items of business are described in the Proxy Statement that follows this notice. Holders of record of the Company’s common stock as of the close of business on January 13, 2026 are entitled to notice of and to vote at the Annual Meeting or any continuation, postponement, or adjournment thereof. A complete list of such stockholders will be open to the examination of any stockholder for a purpose germane to the meeting for a period of ten days before the Annual Meeting at the Company’s principal place of business, located at 4601 Fairfax Drive, Suite 600, Arlington, Virginia 22203. The list of these stockholders also will be available during the Annual Meeting after entering the 16-digit control number included on your Notice of Internet Availability of Proxy Materials, on your proxy card, or on the instructions that accompanied your proxy materials. The Annual Meeting may be continued or adjourned from time to time without notice other than by announcement at the Annual Meeting.

Your vote is important. Voting your shares will ensure the presence of a quorum at the Annual Meeting and will save us the expense of further solicitation. Please promptly vote your shares by following the instructions for voting on the Notice Regarding the Availability of Proxy Materials or, if you received a paper or electronic copy of the Company’s proxy materials, by completing, signing, dating, and returning your proxy card or by Internet or telephone voting as described on your proxy card.

By Order of the Board of Directors Vincent W. MathisSenior Vice President, Chief Legal and Compliance Officer, and Secretary

Arlington, Virginia

January 26, 2026

This Notice of Annual Meeting and Proxy Statement are first being distributed or made available, as the case may be, on or about January 26, 2026.

Important Notice Regarding the Availability of Proxy Materials for the Stockholder Meeting:

This Proxy Statement and the Company’s 2025 Annual Report are available free of charge at

www.proxyvote.com.