Miller won several medals at the Cerebral Palsy World Championships in 2005, including gold in the F32 club and gold in the F32 discus.
He has won gold in the club throw at the 1996 Paralympic Games in Atlanta, the 2000 Paralympics in Sydney and the 2004 Paralympics in Athens. He set a world record of 33.53m in that event at the Athens Games. At the 2000 games he also took a bronze medal in the discus throw. Before his attempts to win gold in London, he was presented with a Newcastle united shirt by manager Alan Pardew as good luck.