Castillo was recalled from Triple-A Toledo on Sunday, Cody Stavenhagen of The Athletic reports.
Castillo has been dominant in the minors this year, posting a 1.79 ERA and 1.20 WHIP in 40.1 innings over 39 appearances at Toledo. He's tossed two scoreless innings in the majors and will rejoin the Tigers' bullpen after Michael Pineda was designated for assignment Sunday.