Seattle announced the moves before its game at the Brewers on Sunday. The Mariners opened up a spot for first baseman Russell Branyan, who was acquired in a trade with the Indians late Saturday, by sending first baseman Mike Carp to Triple-A Tacoma.
Sweeney has a history of back problems and had just come off the DL on June 17 with lower back inflammation. He missed one game following a start at first base Friday night. He was hitting .263 with six homers and 18 RBIs in 30 games.