The Mariners also sent down catcher Jamie Burke.
Beltre had surgery to remove bone spurs from his bothersome left shoulder. The two-time Gold Glove winner is expected to miss six to eight weeks. He was batting .259 with five home runs and 31 RBIs.
Mariners manager Don Wakamatsu said the surgery went well and there were no complications. Beltre's move was made retroactive to Monday.
Langerhans was traded Sunday from Washington to Seattle for infielder Mike Morse. The 29-year-old Langerhans had spent the entire season in the minors, and the Mariners selected his contract from Triple-A Tacoma.
Burke was outrighted to Tacoma. He hit .122 with one home run in 13 games for Seattle.