A strong and skillful footballer, Dunn who was six-foot tall overcame a slow start to his league career at Sturt to develop into an excellent ruckman. He was also used in defence at times during his football career at Sturt.
Dunn made his league debut for Sturt in 1927 and went on to play 74 games for the club, rarely playing a poor one. He represented South Australia on three occasions.
He finished his career at Sturt in style, not only winning the Magarey Medal, but also the best and fairest in the same year.
The following season he moved to Victoria and spent four years with Carlton, playing 38 games in the VFL.