A New South Wales State of Origin and Australian international representative forward, he played club football in Sydney for Eastern Suburbs, Canterbury-Bankstown, Parramatta and Penrith.

In 1988, Dunn was the recipient of the Clive Churchill Medal for his man-of-the-match performance at prop in the Grand Final-winning Canterbury team.

Following this grand final victory, he travelled with the Panthers to England for the 1991 World Club Challenge which was lost to Wigan.

Dunn played one State of Origin game for New South Wales in 1988, and two games in 1989, along with seven Tests and five World Cup matches for Australia between 1986 and 1988, but found it hard to press for further representative honours in an era dominated by powerful forwards including Steve Roach, David Gillespie, Paul Harragon, Paul Sironen and John Cartwright.

Appointed the chief executive of the newly re-instituted South Sydney Rabbitohs, Dunn departed the club after its disappointing return season of 2002 due to unrest within the organisation.