The son of a local lawyer, William Charles Ainsworth, Geoff matriculated to the University of Melbourne in 1965, where he was resident at Trinity College.
[2] He was a member of Geelong's losing 1967 VFL Grand Final side in his first year at the club.
[2] After missing all but one game of the 1971 season as he was travelling in Europe, Ainsworth went on to become club captain in 1973.
[2] He lost the captaincy role the following season and retired, aged only 28, at the end of the year in order to concentrate on his legal career.
This Australian rules football biography of a person born in the 1940s is a stub.