With the Rays out of contention, they told the 25-year-old left-hander of their decision before Tuesday night's game at the New York Yankees.
Smyly was 9-10 with a 3.24 ERA, including 3-1 with a 1.70 ERA since he was acquired from Detroit on July 31 as part of a three-team trade that sent ace David Price from the Rays to the Tigers. Smyly's previous high was 126 innings for Class A Lakeland and Double-A Erie in 2011. His 2012 season was interrupted by injuries and he pitched out of the bullpen last year.
Rays manager Joe Maddon said a player likely would be brought up from the minors to take Smyly's turn in the rotation Friday at Toronto.