[11] Mavin made his debut with the South Sydney club as a 19-year-old on 27 February 1987[12] and scored his first try in round 4 when he crossed for a double against the Penrith Panthers at Redfern Oval.
[10] Mavin is remembered for his performance in the 1987 sudden death semi final against the Canberra Raiders when he made a number of errors that led to him being replaced in the first half of the game before South Sydney were eliminated from the competition 46–12.
[15] In 2017, it was revealed that Mavin left the ground at half-time after being substituted and watched the second half from the Cauliflower Hotel in Waterloo.
[22] Mavin was later released by Souths and trialled with the Newcastle Knights and St George Dragons but decided to retire at the age of 25.
[23] One of Mavins' tries was shown in the much publicized first Tina Turner rugby league advertisement in 1988[24] in which she sang the song What You Get Is What You See.