King began competing in the F.I.M. world championships in 1993 and clinched the 500cc title in 1996 riding for the KTM team. He was New Zealand's first-ever motocross world champion. In 1997 he finished in third place behind Joël Smets and his older brother Darryl King. He now competes in New Zealand and Australia, winning the New Zealand national championship in 2003. King was inducted into the New Zealand Motorcycle Hall of Fame in 2008.