Juniors

Sullivan's family moved from Melbourne to Adelaide in the late 1970s, and as a child Sullivan played Australian Rules Football, but became interested in speedway when it became obvious that he was not of the ideal build to be a league footballer.

His parents bought him a junior speedway bike and he had his first ride at the Olympic Park Speedway in Mildura in 1985, although his home track was the Sidewinders Speedway in the Adelaide suburb of Wingfield, a 112m long track run by the Sidewinders Junior Speedway Club solely aimed at junior Motorcycle speedway development. Within a few seasons Sullivan was seen as one of the best junior riders in South Australia, winning the South Australian Under-16 Individual title in 1990 and 1991 while winning the Pairs Championships in 1988, 1989, 1990 and 1991.

Sullivan finished in second place at the 1990 Australian Under-16 Championship in Perth behind future Australian teammate and three time World Champion Jason Crump. He would go one better on 12 January 1991 winning his first individual Australian title at his home track in Adelaide.

Ryan Sullivan won three Australian Under-16 Pairs Championships, first in 1989 with that year's National Individual Champion Brett Tomkins, and backing that up in 1990 teaming with fellow Adelaide rider Troy Norvil. He won his third and last junior pairs title on 13 January 1991 paired with Brett Woodifield, a week before his 16th birthday at which time he would graduate into the senior ranks. Due to e missed winning the

Seniors

Sullivan's first senior speedway championship came on 14 April 1991 when he won the track championship at the Westline Speedway in South Australia's "steel city" Whyalla, just three months after graduating to the senior ranks. Sullivan was unbeaten in the heats to finish on 12 points, 4 clear of meeting favourite Brett Tomkins before going on to win the final from Paul Schevienen and Troy Norvill.

After having gained his motor mechanic qualifications at age 19, Sullivan was regarded one of the best young riders in Australia, going on to win three South Australian Championships in succession in 1995, 1996 and 1997, and the Australian Under-21 Championship in 1993 and 1996 (the championship was not held in 1994 or 1995). Other than his 1993 Under-21 title which was won at the Olympic Park Speedway in Mildura, his 1996 U/21 title and his state title wins came at his home track, the North Arm Speedway. As North Arm closed at the end of the 1997 season, Sullivan is the last rider to win the SA Championship at the track.

One of the first big wins of Sullivan's career came when he took out Round 4 of the 1996 Australian Speedway Masters Series 500 at the 510 metres (560 yd) Wayville Showground at home in Adelaide, holding out England's multiple Long Track World Champion Simon Wigg in the final.

Sullivan scored his first podium finish in the Australian Championship in 1997 at the 450 metres (490 yd) Brisbane Exhibition Ground when he finished equal second on points with Jason Crump, but lost a run-off to Crump and was credited with third place. He again finished in third place in 2002 at the Wayville Showground.

In 2004, Sullivan became the first South Australian rider to win the Australian Championship since John Boulger in 1973 when he won the first year that the championship was run as a series (held over 3 rounds), rather than the single meeting format that had been in place since the first running of the title in 1926. Sullivan was undefeated over the three rounds held at the Gold Coast, Gosford and Olympic Park speedways. He defeated defending champion Leigh Adams who finished 2nd in all three rounds, with 1990 World #3 Todd Wiltshire finishing in third with 2 fourth and 1 third placings. This would prove to be Sullivan's only Australian Championship win and the final time he stood on the podium of the event.