The Mariners claimed Watson off waivers from Detroit on Saturday and optioned him to Triple-A Tacoma.
Watson was DFA'd by the Tigers on Wednesday despite having posted a 3.27 ERA and 1.09 WHIP across 55 innings with the team's Triple-A affiliate. The 29-year-old righty has yet to make his MLB debut, but he could receive an opportunity to pitch for Seattle at some point if he continues to pitch well at Tacoma.