Item 5.02. Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers. CECO Environmental Corp. (the “ Company”) announces the departure of Lynn Watkins-Asiyanbi, the Company’s Senior Vice President and Chief Administrative and Legal Officer. Ms. Watkins-Asiyanbi is expected to cease serving as an officer of the Company as of July 31, 2025 and to complete the transition of her role and cease employment as of August 15, 2025 (the “ Departure Date”). During her time at the Company, Ms. Watkins-Asiyanbi was a member of the Company’s executive leadership team and played an active role in the advancement of the organization over the last three (3) years. The Company expresses its thanks to her for her contributions. On July 18, 2025, Ms. Watkins-Asiyanbi and the Company entered into a written separation agreement and release (the “ Separation Agreement”), providing for certain severance payments and benefits to Ms. Watkins-Asiyanbi and a general release of claims in favor of the Company. Pursuant to the Separation Agreement, in exchange for Ms. Watkins-Asiyanbi’s execution and non-revocation of a general release of claims contained in the Separation Agreement, as well as her re-affirmation of certain non-disparagement, non-competition and non-solicitation covenants, she will receive (subject to applicable taxes) certain compensation and benefits, consisting of: (1) $300,000 as a lump sum cash severance payment; (2) a lump sum cash payment equal to nine months of COBRA premiums for continued health care insurance coverage; (3) $20,000 as a lump sum cash payment, which is intended to cover outplacement services; (4) $225,000 as a lump sum cash payment representing 75% of Ms. Watkins-Asiyanbi’s full-year 2025 annual cash incentive award target opportunity; (5) continued vesting of any service-based restricted stock units (“ RSUs”) that remain unvested and outstanding as of the Departure Date that have a scheduled vesting date on or prior to March 31, 2026, with any other RSUs that will not vest during that period forfeited as of the Departure Date; and (6) the target number of performance-based restricted stock units (“ PRSUs”) that remain unvested and outstanding as of the Departure Date that were otherwise scheduled to vest in March 2026 will convert to RSUs and vest on March 15, 2026, with any other PRSUs forfeited as of the Departure Date. The provision of the foregoing compensation and equity vesting under the Separation Agreement is subject to Ms. Watkins-Asiyanbi’s compliance with the terms of the Separation Agreement. The foregoing description of the Separation Agreement is a summary only and is qualified in its entirety by reference to the full text of the Separation Agreement, which is filed as Exhibit 10.1 to this Current Report on Form 8-K and is incorporated herein by reference.

Item 9.01. Financial Statements and Exhibits. (d) Exhibits Exhibit No. Description 10.1 Executive Separation Agreement and Release, dated July 18, 2025, between CECO Environmental Corp. and Lynn Watkins-Asiyanbi. ───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────── 104 Cover Page Interactive Data File (embedded within the Inline XBRL document). 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: July 24, 2025 CECO Environmental Corp. ─────────────────────────────────────────────────────────────────────────────────────────────── By: /s/ Peter Johansson Peter Johansson Chief Financial and Strategy Officer