Geoff Clarkson won cap(s) for Yorkshire (RL) while at Wakefield Trinity.

Geoff Clarkson played at second-row in Wakefield Trinity's 21–9 victory over St. Helens in the Championship Final replay during the 1966–67 season at Station Road, Swinton on Wednesday 10 May 1967.

[8] Geoff Clarkson played at second-row in Leigh's 7–4 victory over St. Helens in the 1970 Lancashire Cup Final during the 1970–71 season at Station Road, Swinton on Saturday 28 November 1970, played at second-row in Leigh's 24–7 victory over Leeds in the 1971 Challenge Cup Final during the 1970–71 season at Wembley Stadium, London on Saturday 15 May 1971, in front of a crowd of 85,514, and played at second-row in Leigh's 8–3 victory over Widnes in the 1981 Lancashire Cup Final during the 1981–82 season at Central Park, Wigan on Saturday 26 September 1981.

Geoff Clarkson extended his record number of transfers to 12 when he left Leigh for Featherstone Rovers on 27 October 1983.

Geoff Clarkson made his début for Wakefield Trinity during December 1965, he played his last match (during his second spell) for Wakefield Trinity during the 1977–78 season, he made his début for Leigh during the 1970–71 season, he played his last match (during his second spell) for Leigh on Thursday 27 October 1983, during the 1983–84 season, he made his début for Warrington on Friday 20 August 1971, he played his last match for Warrington on Sunday 22 October 1972, he made his début for Featherstone Rovers on Sunday 30 October 1983, he played his last match for Featherstone Rovers during the 1983–84 season.