Exhibit 23.1

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We hereby consent to the incorporation by reference in the Registration Statements on Form S-8 (Nos. 333-196973, 333-232925, 333-240195, 333-266696 and 333-273699) of Trinseo PLC of our report dated February 27, 2025 relating to the financial statements, financial statement schedule and the effectiveness of internal control over financial reporting, which appears in this Form 10-K.

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/s/ PricewaterhouseCoopers LLP

Philadelphia, Pennsylvania

February 27, 2025