EXHIBIT 23

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We hereby consent to the incorporation by reference in the Registration Statements on Form S-8 (Nos. 333-226586, 333-211153, 333-203817, 333-184958, 333-174032, 333-158932, 333-148712, 333-145201, 333-145199, 333-85558, 333-53036, and 333-11757) of Tetra Tech, Inc. of our report dated November 23, 2022 relating to the financial statements, financial statement schedule and the effectiveness of internal control over financial reporting, which appears in this Form 10-K/A.

/s/ PricewaterhouseCoopers LLP

Los Angeles, California

August 14, 2023