The 34-year-old played just two matches for TFC in 2015.
Toronto FC defender and former Scotland international Steven Caldwell announced his retirement on Tuesday.
The 34-year-old has struggled with injuries over the past two seasons, and made just two appearances for TFC this year. He steps away from the playing side of the game after a 17-year career, spent mostly in England.
“It’s with a heavy heart that I announce my retirement from the game I love," Caldwell said in a statement. "Football has been my life since a very young age and I appreciate the opportunity I’ve had to live out my dreams.