Grimm's contract was selected by the Athletics on Thursday, Matt Kawahara of the San Francisco Chronicle reports.
Grimm posted a 3.68 ERA and 1.36 WHIP in 7.1 innings across seven appearances as a non-roster invitee this spring, and he'll begin the year with a low-leverage role in Oakland's bullpen. He spent the entirety of 2021 at Triple-A Tacoma with the Mariners and logged a 4.37 ERA and 1.36 WHIP in 47.1 innings.