The tempestuous Bradley, who hit for a .209 average in two seasons with the Mariners, was designated for assignment by the club as general manager Jack Zduriencik made a pair of roster moves to bring up two young power hitters.
"We felt Milton was not part of our future and not part of our present. Therefore, the move was made," Zduriencik told reporters in a conference call, Major League Baseball's official website (www.mlb.com) reported.
Carlos Peguero, 24, was recalled from Class AAA Tacoma to take Bradley's spot. Earlier Monday, Seattle designated another light-hitting outfielder, Ryan Langerhans, for assignment and called up outfielder Mike Wilson, 27, from Tacoma.
The Mariners have won eight of 12 games to improve to 16-19, but scored just 18 runs in their last eight games.
Zduriencik said Peguero and Wilson would be used as a left-right combination in left field.
Bradley's tenure with Seattle was tumultuous, as it has often been over his 12 MLB seasons spent with eight teams.
He was ejected from two games in the past 10 days and sat out another on a one-game suspension.
Bradley, 33, declined to speak with reporters most of this season and wore earplugs during many of his games, apparently to keep from hearing the taunts of fans.
This season, new manager Eric Wedge put Bradley in the middle of his lineup and started him in left field in 26 of the team's first 35 games, but he drove in only three runs, failed to hit a home run and played poorly on defense.
Bradley is still owed the remainder of a $12 million contract for this season.
Peguero, of the Dominican Republic, hit .282 with four home runs and 13 RBIs this season for Tacoma, and Wilson has hit four homers and driven in 14 runs.
The Mariners are still awaiting the return of outfielder Franklin Gutierrez, who remains on the disabled list while recovering from stomach issues that sidelined him during spring training.
(Writing by Larry Fine, Editing by Steve Ginsburg)