Bauers, who had been designated for assignment by Cleveland, has started 25 of the 43 games in which he's appeared for the Indians this season, batting .190 with 2 home runs and 6 RBIs.
He was given Cleveland's starting job despite being outplayed by Bobby Bradley in training camp because he was out of minor league options. Bradley has been recalled.
Bauers is in the Mariners' lineup for Thursday's game in Detroit, and he'll be back in Cleveland on Friday when Seattle opens a three-game series.
In three major league seasons, Bauers has a .211 average with 25 home runs and 97 RBIs. He did not play for the Indians in 2020, spending the abbreviated season at the club's alternate training site.
The 25-year-old Bauers was acquired by Cleveland from Tampa Bay in a three-team deal in 2018.
To make room on the roster, the Mariners designated infielder Jack Mayfield for assignment.
The Associated Press contributed to this report.