Betemit has torn cartilage in his right wrist, and an MRI also revealed "a pretty significant bone bruise," according to Orioles manager Buck Showalter.
The move, announced Thursday, is retroactive to Aug. 12. Showalter expects Betemit to return Aug. 27, when he's eligible to leave the DL.
Betemit is batting .264 with 12 homers and 37 RBIs in 97 games with Baltimore. He's played first base, third base and left field.
The Orioles recalled 25-year-old first baseman Joe Mahoney from Triple-A Norfolk to fill out the roster. Mahoney made his major league debut July 7 against the Angels, going 0 for 3 before being optioned to Norfolk two days later.