The Mariners claimed Speier off waivers from the Royals on Wednesday.
Speier provides the Mariners with an extra left-handed option out of the bullpen heading into 2023, though he's likely to settle for a low-leverage role if he earns a spot on the Opening Day roster. He made 19 appearances for Kansas City in 2022, logging a 2.33 ERA and 1.09 WHIP while striking out 14 in 19.1 innings.