A product of the Walsall youth system, he signed for the club on amateur terms in June 1961 before turning professional on 13 November 1963.^[1] His league debut came in September 1964 against Southend United and in his early days at the club he was employed as a Utility player before settling into the role of full back.^[1] He established himself as first choice in that position for a number of years until suffering an injury in 1979 which saw him miss all but one of the league games in the 1979-80 season though he did make two substitute appearances also.^[1] He returned for 19 league appearances the following season and made his final appearance in a game against Chesterfield in September 1981.^[1] He also acted as trainer of the reserves around this time.^[1] Harrison made in total either 467^[2] or 473^[3] league appearances depending on the source consulted. He left the club in 1982 and continued playing in the non-league with Rushall Olympic for a number of seasons before retiring.^[1]

Harrison's record for most Walsall appearances in all competitions was overhauled by Jimmy Walker in January 2012.^[4] As of January 2012 however he still holds the league appearances record for the club.