UNITED STATES
SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934

Date of Report (Date of earliest event reported) May 18, 2026

Comfort Systems USA, Inc.

(Exact name of registrant as specified in its charter)

Registrant’s telephone number, including area code (713) 830-9600

(Former name or former address, if changed since last report.)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

¨ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

¨ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

¨ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

¨ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company ¨

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ¨

ITEM 5.07 Submission of Matters to a Vote of Security Holders.

On May 18, 2026, the Company held its 2026 Annual Meeting of Stockholders. Of the 35,183,967 shares of common stock outstanding and entitled to vote at the Annual Meeting, 31,221,297 shares were present in person or by proxy, constituting a 88.74% quorum. The matters submitted to the stockholders of the Company at the Annual Meeting, and the results of the voting, were as follows:

Proposal No. 1.        Vote regarding the election of Darcy G. Anderson, Herman E. Bulls, Rhoman J. Hardy, Gaurav Kapoor, Brian E. Lane, Pablo G. Mercado, Franklin Myers, William J. Sandbrook, Constance E. Skidmore, and Cindy L. Wallis-Lage as members of the Board of Directors:

There were 1,788,538 broker non-votes as to Proposal No. 1.

Proposal No. 2.        Vote regarding ratification of the appointment of Deloitte & Touche LLP as the Company’s independent registered public accounting firm for the year ending December 31, 2026:

There were no broker non-votes as to Proposal No. 2.

Proposal No. 3.       Advisory vote regarding approval of the compensation paid by the Company to its named executive officers:

There were 1,788,538 broker non-votes as to Proposal No. 3.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

Date:     May 21, 2026