Sheffield was designated for assignment by the Mariners on Thursday.
Sheffield made double-digit appearances in the majors in 2020 and 2021 but was limited to just six appearances (one start) for the Mariners last year. He posted a 3.86 ERA and 1.29 WHIP in 11.2 innings and will lose his spot on the 40-man roster after the team signed Tommy La Stella on Thursday.