FEDERAL SIGNAL CORP /DE/

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. __)

Filed by the Registrant þ

Filed by a Party other than the Registrant¨

Check the appropriate box:

1333 Butterfield Road, Suite 500, Downers Grove, Illinois 60515

Notice of Annual Meeting of Stockholders To Be Held on Tuesday, April 21, 2026

To the Stockholders of Federal Signal Corporation:

We look forward to your attendance at the Annual Meeting of Stockholders of Federal Signal Corporation, a Delaware corporation (the “Company”), on Tuesday, April 21, 2026, at 8:30 a.m., Central Daylight Time (the “Annual Meeting”). The Annual Meeting will be held in person at the Company’s Corporate Offices located at 1333 Butterfield Road, Suite 500, Downers Grove, IL 60515.

The Annual Meeting will be held for the following purposes:

•To elect eight directors;

•To approve, on an advisory basis, the compensation of our named executive officers (“NEOs”);

•To ratify the appointment of Deloitte & Touche LLP as our independent registered public accounting firm for fiscal year 2026; and

•To transact such other business that may properly come before the meeting or any adjournment(s) or postponement(s) thereof.

The Board of Directors of the Company (the “Board”) has fixed the close of business on February 23, 2026, as the record date for the Annual Meeting. Only stockholders of record on the record date are entitled to receive notice of, and to vote at, the Annual Meeting.

The Board recommends that you vote “FOR ALL” the director nominees proposed by the Board; “FOR” the advisory approval of our NEO compensation; and “FOR” the ratification of the appointment of Deloitte & Touche LLP as our independent registered public accounting firm for fiscal year 2026.

Stockholders of record on the record date will receive a Notice of Internet Availability of Proxy Materials (the “Notice of Internet Availability”). The Notice of Internet Availability, first mailed on March 6, 2026, contains instructions on how to access the proxy statement, this notice, and our 2025 Annual Report on Form 10-K on the Internet atwww.proxyvote.com. Stockholders wishing to receive a printed copy of our proxy materials should follow the instructions provided in the Notice of Internet Availability. Those stockholders who previously requested printed or electronic copies of our proxy materials will receive a printed or electronic copy, as applicable.

To vote, please follow the instructions in the Notice of Internet Availability or the proxy materials if you received printed copies. If you vote by telephone or via the Internet, you do not need to return a proxy card. If you attend the Annual Meeting, you may vote your shares during the meeting. If you hold your shares through a broker or other custodian, please check the voting instructions provided to you by that broker or custodian.

YOUR VOTE IS IMPORTANT! Whether or not you expect to attend the Annual Meeting, please vote your shares at your earliest convenience. This will ensure the presence of a quorum at the Annual Meeting and save the extra expense of additional solicitation. Submitting your proxy now will not prevent you from voting your shares at the Annual Meeting, as your proxy is revocable at your option. If you have any questions or need assistance in voting your shares of our common stock, please call the Corporate Secretary at (630) 954-2009 or email us atinfo@federalsignal.com.

By order of the Board of Directors,

Diane I. Bonina, Corporate Secretary

March 6, 2026