Bedard, the big prize in last winter's blockbuster trade with Baltimore, will be eligible to return to the mound on July 20.
Bedard, who's 6-4 with a 3.67 ERA in 15 starts for Seattle this season, last pitched five innings on July 4. He was not scheduled to pitch until after the All-Star break.
"We felt placing Bedard on the disabled list gave us some extra flexibility over the next week," Mariners general manager Lee Pelekoudas said in a club release. "It doesn't change when he would next pitch, and it allows Jim [Riggleman] to have an extra arm in the bullpen."
Bedard's exit from the active roster came on the same day as the release of veteran first baseman Richie Sexson. To fill the two roster spots, Seattle promoted right-handed pitcher Jared Wells and infielder Tug Hulett from Tacoma.
Jim Street is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.