Sidelined for the past four games because of inflammation, Sweeney was shut down for at least two weeks and replaced on the active roster by first baseman Mike Carp, who was promoted from Triple-A Tacoma.
Carp was in uniform and available for Monday night's series opener against the Rangers.
Carp, 23, appeared in 50 games with the Rainiers this season, hitting .250 with eight doubles, 10 home runs and 31 RBIs. In five June games, Carp was hitting .400 (8-for-20) with a double, a home run and three RBIs.
He batted .315 in 54 at-bats for the Mariners last season.
Sweeney was one of the Mariners' hottest hitters in May, batting .310 (18-for-28) with two doubles and six home runs.
Also on Monday, the Mariners sent catcher Adam Moore to Tacoma on a rehab assignment. He has been sidelined for two weeks with a leg injury.
Jim Street is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.