The deal was made official Wednesday. The Orioles also designated right-hander Steve Johnson for assignment.
The past two seasons, Trumbo has averaged 18 homers and 64 RBIs, posted a .303 OBP and averaged 0.2 WAR per season. He was a little better in 2015 after an injury-plagued 2014, but he hit just .263/.316/.419 with the Mariners -- poor numbers for a first baseman or DH. However, Trumbo averaged 34 home runs and 94 RBIs per season with the Angels from 2011 to 2013, but a .300 OBP held his value to 2.5 WAR per season.
Clevenger, a Baltimore native, joined the Orioles via a 2013 trade with the Chicago Cubs, but he played in fewer than 40 games each season with the Orioles, as he was primarily used as a backup. Last season was Clevenger's most productive in Baltimore; he hit two home runs, drove in 15 runs and batted .287.
By acquiring Trumbo, the Orioles might be preparing for the departure of first baseman Chris Davis. Davis is coming off of a 47-homer season and is the biggest bat on the free-agent market.
ESPN's David Schoenfield contributed to this report.