Jones started competing in triathlons in 1990. In 1992 and 1993 she won the ITU Triathlon World Championships. In 1996, she won the inaugural XTERRA Triathlon World Championships. Jones would go on to further expand her triathlon résumé by winning the ITU Triathlon World Cup in 1998 and 1999. At the 2000 Summer Olympics Jones took the Silver Medal in the inaugural triathlon event with a total time of 2:00:42.55, only two seconds behind Gold Medalist Brigitte McMahon. Her split times were 19:43.88 for the swim, 1:05:32.90 for the cycling and 0:35:25.77 for the run.
After recently expanding into Iron distance competition, Jones took second place in the 2005 Ironman World Championship, losing the lead during the run to Natascha Badmann. This was only the second time that she competed in an iron distance triathlon. Later she won the 2006 Ironman Arizona Triathlon, finishing with a time of 9:12:53, and the Ironman Triathlon in Kailua-Kona, Hawaii in 9:18:31. With this victory, Jones became the first Australian woman to win a World Ironman Championship and it made her the second Australian in history to win the event, behind 1994 Men's World Champion, Greg Welch.