The Argos have released the veteran quarterback less than two seasons after signing him to be their starter.
The former NFL pivot appeared in 25 regular-season and two playoff games with Toronto, compiling a 11-14 record overall.
Toronto was just 2-6 with him under centre this season.
The Argos released Lemon after he was benched in the second half of their 29-16 home loss to the B.C. Lions on Friday night.
Lemon was 11-of-15 passing versus the Lions for just 57 yards.
The move comes with veteran quarterback Steven Jyles scheduled to come off the nine-game injury list this week. Argos head coach/GM Jim Backer has said Jyles will immediately be added to the Argos' 46-man roster.
Lemon completed 430-of-680 passes with Toronto (63.2 per cent) for 5,069 yards but had more interceptions (23) than touchdowns (22).