Material Event (Form 8-K)

On September 3, 2025, Sotera Health Company, certain stockholders named in Schedule 2 thereto (the "Selling Stockholders") and Goldman Sachs & Co. LLC, as underwriter (the "Underwriter"), entered into an underwriting agreement (the "Underwriting Agreement") relating to the sale of 20,000,000 shares (the "Shares") of the Company's common stock, par value $0.01 per share ("Common Stock") by the Selling Stockholders, at a price of $15.111 per share, subject to and upon the terms and conditions set forth therein. On September 5, 2025, the Selling Stockholders sold the Shares to the Underwriter pursuant to the Underwriting Agreement. The Company did not issue or sell any shares of Common Stock in that transaction and will not receive any proceeds from the sale of the Shares by the Selling Stockholders.

The foregoing description of the Underwriting Agreement does not purport to be complete and is qualified in its entirety by reference to the Underwriting Agreement, which is filed herewith as Exhibit 1.1 and is incorporated herein by reference. The opinion of Cleary Gottlieb Steen & Hamilton LLP, relating to the validity of the Shares, is filed as Exhibit 5.1 hereto.