FUELCELL ENERGY INC

FuelCell Energy, Inc. (referred to in this Proxy Statement as “we,” “FuelCell”, “FuelCell Energy” or the “Company”) is providing you with this Proxy Statement in connection with the solicitation by FuelCell’s Board of Directors (the “Board”) of proxies to be voted at FuelCell’s 2024 Annual Meeting of Stockholders (the “Annual Meeting”) and at any adjournment or postponement thereof. The Annual Meeting will be a completely “virtual meeting” of stockholders to be held on Thursday, April 4, 2024 at 1:00 p.m. Eastern Daylight Time. You will be able to attend the Annual Meeting as well as vote and submit your questions during the live audio webcast of the meeting by visitingwww.virtualshareholdermeeting.com/FCEL2024and entering the 16-digit control number included in our notice of internet availability of the proxy materials, on your proxy card or in the instructions that accompanied your proxy materials. The Company is a Delaware corporation. The address of our principal executive office is 3 Great Pasture Road, Danbury, Connecticut 06810.

The Board has set the close of business on February 5, 2024 as the record date for the determination of holders of the Company’s common stock, par value $0.0001 per share, who are entitled to notice of, and to vote at, the Annual Meeting.

As of February 5, 2024, there were 450,684,628 shares of common stock outstanding and entitled to vote at the Annual Meeting. Holders of common stock outstanding at the close of business on the record date will be entitled to one vote for each share held on the record date.

We are providing access to our proxy materials online under the U.S. Securities and Exchange Commission’s “notice and access” rules. As a result, we are mailing to many of our stockholders a notice instead of a paper copy of this Proxy Statement and our Annual Report. The notice contains instructions on how to access documents online. The notice also contains instructions on how stockholders can receive a paper copy of our materials, including this Proxy Statement, our Annual Report and a form of proxy card or voting instruction card. Those who do not receive a notice, including stockholders who have previously requested to receive paper copies of proxy materials, will receive a paper copy by mail unless they have previously requested delivery of materials electronically.

The Notice of Annual Meeting, Proxy Statement and proxy card are first being distributed and made available to our stockholders on or about February 16, 2024.

Important Notice Regarding the Availability of Proxy Materials for the Annual Meeting of Stockholders to be Held on April 4, 2024: The Notice of Annual Meeting, Proxy Statement and Annual Report to Stockholders for the fiscal year ended October 31, 2023 are available atwww.proxyvote.com** (using the 16-digit control number included in our notice of internet availability of proxy materials, on your proxy card or in the instructions that accompanied your proxy materials), as well as on our website atwww.fuelcellenergy.com.**

Proxy Summary