The move before Monday night's game at Texas is retroactive to Thursday, and comes after the 36-year-old, five-time All-Star had a streak of power hitting that Seattle's offense desperately needs. Sweeney is again battling low-back pain.
He is hitting .258 with six home runs and 16 RBIs in 27 games.
The 23-year-old Carp was hitting .250 with 10 homers and 31 RBIs in 50 games for Tacoma. The left-handed hitter played in 21 games for Seattle last season.