Forsyth was a reserve to travel in Featherstone Rovers' 17-12 victory over Barrow in the 1966–67 Challenge Cup Final during the 1966–67 season at Wembley Stadium, London on Saturday 13 May 1967, in front of a crowd of 76,290.
He played at prop (replaced by substitute Graham Joyce) in Bradford Northern's 18-8 victory over York in the 1978–79 Yorkshire Cup Final during the 1978–79 season at Headingley, Leeds on Saturday 28 October 1978.
[citation needed] He played at prop in Bradford Northern's 6-0 victory over Widnes in the 1979–80 John Player Trophy Final during the 1979–80 season at Headingley, Leeds on Saturday 5 January 1980.
In July 1980, he was sold to Wakefield Trinity as part of an exchange deal for Graham Idle.
[7] Colin Forsyth won caps for England while at Bradford Northern in the 1975 Rugby League World Cup against France, New Zealand, and Wales.