Mavin played a total of 101 first grade games which included 89 for the South Sydney Rabbitohs and 12 for the Canterbury Bankstown Bulldogs. Mavin made his debut with the Rabbitohs as a 19-year-old on 27 February 1987 and scored his first try in round 4 when he crossed for a double against the Penrith Panthers at Redfern Oval. Mavin played in every game of the 1987 NSWRL season and scored a total of 27 tries during his career. Mavin is remembered for his performance in the 1987 sudden deathsemi 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 the Rabbitohs were eliminated from the competition 46–12. 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. Mavin later said of the game "A bit later, Ian Roberts and David Boyle came to get me. They said the team function was at Maroubra Junction and that I should come along. I was like, ‘Ah … what can I do?’ But I went along and it was OK. Wally Lewis was there. He sort of gave me the thumbs up. But mate I was pretty inconsolable". Mavin would spend three more years with Souths including the 1989 season when he played in every game and the Rabbitohs were minor premiers. He then played the 1990 off-season with English club Trafford Borough and one year with Canterbury in 1991. He returned to Souths in 1992 and broke his leg in Round 1 against the Parramatta Eels. 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. Mavin was a big and fast flamboyant centre/winger who was also well known for his swan dive tries. One of Mavins' tries was shown in the much publicized first Tina Turnerrugby league advertisement in 1988 in which she sang the song What You Get Is What You See. In 2008 Mavin was named in the Alexandria Rovers "60 Year Best of Team".
Personal life
Since 2006 Mavin has worked as a Stevedore on the Port Botany waterfront. In 2019 Mavin began co-hosting Rabbitohs Radio, a weekly rugby league podcast covering the South Sydney Rabbitohs. In the podcast Mavin, former teammate Darren Brown & Grant Chappell examine Rabbitohs team news, performances & interview special guests.