In 1989 he was part of the Queensland State of Origin team's 3-0 clean sweep of New South Wales, playing all three games in the second-row. He was chosen to tour New Zealand with the Australian squad in 1989 but was forced to pull out with a broken hand. The following year, he announced his retirement from representative football so he could concentrate on his job as captain of the fledgling Brisbane club, helping the Broncos to the play-offs for the first time in 1990.
After 72 first grade games for the Broncos, 14 Tests for Australia (including two Kangaroo tours) and 19 State of Origin matches for Queensland, Miles accepted a contract offer from Wigan, making his debut in October 1991 against Featherstone Rovers. Miles played 29 matches for Wigan as they won a treble of Championship, Challenge Cup and Premiership. Whilst at Wigan, Miles formed a formidable partnership with winger Martin Offiah.
Initially one of a group of fast and skillful heavyweight Queensland centres along with Mal Meninga and Chris Close, Miles size saw him moved into the Second-row towards the end of his Australian career, though he generally played in the centres with Wigan. Miles was particularly skilled in passing, and noted for his ability to use his 6'4" (193 cm) height to his advantage and off-load the ball with a one-handed basketball style.
Miles returned to Australia to pursue a media career with Channel Nine and in 2000, was awarded the Australian Sports Medal for his contribution to Australia's international standing in the sport of rugby league. In 2001 Miles was appointed Chairman of Selectors for the Queensland State of Origin. He is also the Executive Director of the non-profit organisation Former Origin Greats (FOGS).
During the 2007 season at the Broncos' 20-year anniversary celebration, the club announced a list of the 20 best players to play for them to date which included Miles.