Gallen rejected the Diamondbacks' one-year, $22.025 million qualifying offer Tuesday, Jon Heyman of the New York Post reports.
The decision was anticipated, and Gallen will now seek a multi-year contract on the free-agent market. If he departs Arizona, the Diamondbacks will receive a draft pick as compensation. Gallen posted a career-worst 4.83 ERA in 2025, but he had a career 3.29 ERA with a 26.6 percent strikeout rate coming into the season. The 30-year-old should have little trouble landing a lucrative multi-year contract.