Bradley made his senior football debut in 1981 as a seventeen-year-old for Port Adelaide in the South Australian National Football League (SANFL), Port’s third premiership in a row. At the end of 1981 Victorian Football League club Essendon approached Bradley to join them but he turned down the offer, wishing to remain in South Australia with Port Adelaide and to build on his promising cricket career.

In 1982, his second season, Bradley won Port Adelaide’s Best and Fairest.

In 1984 Bradley would be selected in the Australian team to take on Ireland in the revival of the International Rules series.

In 1985 Bradley had won his third consecutive Port Adelaide best and fairest and was runner-up for the Magarey Medal.

After 89 games with Port Adelaide, Bradley was recruited by VFL club Carlton in 1986 as part of a recruiting drive that also netted future captain Stephen Kernahan and Peter Motley.

Bradley won three Robert Reynolds Trophies as Carlton’s Best & Fairest, in 1986, 1988 and 1993, as well as being a member of the 1987 and 1995 premiership sides. Bradley played with Carlton for seventeen seasons, acting as Kernahan’s vice captain from 1990 until 1997, then captaining Carlton from 1998 to 2001.

In this time, Bradley also represented Australia three times in the International Rules series, including as vice-captain in 2000 and captain in 2001. He broke Bruce Doull’s Carlton games record in Round 1, 2002.

Bradley’s final AFL game, against Port Adelaide, was in Round 19, 2002, polling 3 Brownlow Votes at the age of 38 years and 289 days, making him the sixth-oldest player in the history of the league. His final appearance overall was in the 2002 International Rules series.

In November 2002, following Carlton’s salary cap breach which lost the club valuable draft picks, Bradley had contemplated reversing his decision to retire and attempt to rebuild a club in crisis, but he eventually stood by his initial decision to retire from the game, which was made three weeks before the salary cap drama occurred.

Bradley also played 27 matches in Night Series competition with Carlton, but these are not counted as senior games by the AFL. Taking the AFL’s view, Bradley’s 500th game was the first International Rules test against Ireland at Croke Park in 2002.

Bradley’s services to the game have been officially recognised several times at the highest levels. He was immediately inducted into the Australian Football Hall of Fame in 2006, after the minimum three years of retirement. At Carlton, Bradley is an Official Legend of the club’s Hall of Fame, and was selected on the wing in the club’s Team of the Century. He was also selected on the wing in Port Adelaide’s Team of the Century.

In 2007, Bradley returned to Carlton as a part-time assistant coach.