Exhibit 31.3
CERTIFICATION OF CHIEF EXECUTIVE OFFICER
I, Frank Bozich, certify that:
1. | I have reviewed this Amendment No. 1 to the annual report on Form 10-K/A of Trinseo PLC; |
2. | Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report; |
Date: April 27, 2026
| By: | /s/ Frank Bozich |
| Name: | Frank Bozich |
| Title: | Chief Executive Officer |