Wittgren signed a minor-league contract with the Mariners on Sunday, Jon Heyman of the New York Post reports.
Wittgren found work with Seattle after recently parting ways with the Royals, who moved him off the 40-man roster after he posted a 4.97 ERA in 27 appearances this season. He had four saves, 22 holds and a 2.99 ERA for Cleveland between the 2019 and 2020 campaigns, but he's struggled to a 5.24 ERA over the past three seasons.