The Mariners non-tendered Thornton on Friday, Daniel Kramer of MLB.com reports.
Thornton's 2025 season came to an abrupt halt in late July after he tore his left Achilles tendon. Prior to the injury, Thornton posted five holds along with a 4.68 ERA, 1.30 WHIP and 32:14 K:BB across 42.1 innings while operating out of the bullpen. Thornton's expected timeline to recover was estimated as 6-to-8 months after undergoing surgery in August, which will impact his availability for spring training should he sign with a team.