Montero batted .223/.250/.411 with five home runs, 19 RBI, 32 strikeouts and four walks in 116 plate appearances with Seattle last season. The 26-year-old also posted a .966 OPS with 18 homers in 98 games at triple-A.
The Venezuelan initially signed with the New York Yankees as an amateur free agent in 2006 and soon became one of the top prospects in baseball. The Yankees sent him to Seattle to land starting pitcher Michael Pineda in 2012.
Montero has appeared in 226 career games with the Yankees and Mariners, hitting .253 with 28 career home runs.
In order to make room for Montero on the roster, the Blue Jays designated catcher A.J. Jimenez for assignment.