The Cubs selected Wantz's contract from Triple-A Iowa on Monday.
Wantz will provide the Chicago bullpen with a fresh arm capable of covering multiple frames after the Cubs needed three relievers to handle the final four innings of Sunday's 8-7 loss to the Pirates. The 30-year-old righty made one appearance in the big leagues with the Rays earlier in 2026 but has otherwise spent the entire season at the Triple-A level, where he's produced a 5.63 ERA, 1.65 WHIP and 49:26 K:BB over 48 innings.