Exhibit 99.1 Willdan Group Reports Fourth Quarter/Full Year 2023 Results and Provides 2024 Outlook ANAHEIM, Calif. –March 7, 2024 – Willdan Group, Inc. ("Willdan") (Nasdaq: WLDN) today reported financial results for its fourth quarter and fiscal year ended December 29, 2023 and outlook for 2024. "We had an exceptional fourth quarter," said Mike Bieber, Willdan's President and Chief Executive Officer. "Revenue, profitability and cash flow were above our expectations, aided by end of year program expansions. ...