Johnson played 5 years in the CFL with Calgary an Toronto, though more than half of his output came from his one big season in 1986. Johnson signed with Calgary in August of 1985, appearing in 11 games in his rookie season with 167 pass attempts. Johnson took over the starting QB job in 1986, leading the league in passes (604), completions (302) and yards (4379). He also threw 31TD passes and was named to both the Wes and All-Canadian All-Star teams. Injuries limited JOhnson to just 10 games in 1987 with his completion percentage dipping under 50% to 47.9% and with 17 interceptions to only 7 touchdown passes. Johnson retired in August of 1988, after playing just three games that season. Toronto signed him as a free agent in September of 1989 and he played 6 games for the Argos. Johnson was then part of a huge trade with the BC Lions in March of 1990, that brought QB Matt Dunigan to the Argos for Johnson, DB Todd Wiseman, DL Jearld Bayliss, LB Tony Visco, WR Emanual Tolbert and LB Willie Pless. Johnson never saw any action with the Lons.