To make room on their roster for Wells, the Blue Jays have designated right-hander Alex Burnett for assignment. The 25-year-old owns a career ERA of 4.61 over parts of three seasons in the majors.
The Mariners designated Wells for assignment at the end of spring training, as he wasn't able to claim a spot on their bench. Instead, Seattle elected to enter the regular season with veteran Jason Bay as their fifth outfielder.
At this point, the Blue Jays' roster includes outfielders Jose Bautista, Melky Cabrera, Rajai Davis and Colby Rasmus, while Mark DeRosa can also man the corner positions.
Wells appeared in 93 games with the M's last season, hitting .228/.302/.396 with 12 doubles, three triples and 10 home runs over 316 plate appearances. Seattle acquired the 28-year-old from the Detroit Tigers in the Doug Fister trade.
Over parts of three seasons in the majors, Wells owns a career batting line of .246/.317/.435.