Robertson, who won legions of fans around the world for his aggressive, all-or-nothing racing style, said: "I'm extremely proud of what I was able to achieve throughout my career - not simply the results, but the fact that I followed and achieved my dreams."

He took his third world title after an unforgettable run in the oppressive heat at Gamagori, Japan in the 2005 ITU Triathlon World Championships.

After entering the final transition with a group of more than 50 athletes, Robertson took the initiative early in the final 10 kilometres run and led throughout.

Previously, he claimed his second world title in 2003 in Queenstown, New Zealand, after a bold move to break away from the main pack.

But the pinnacle of his career was tied to triathlon's Olympic Games debut in his home country.

"My dream as a kid was to go to the Olympics and in 2000, when I won the Sydney ITU World Cup, I achieved my childhood dream, qualifying for the Olympic Games, in front of the very people who had helped me achieve this goal," said Robertson.

"This is without doubt my most memorable sporting moment - all my other results were just icing on the cake.

"I'd like to take this opportunity to thank everyone who was involved throughout my career, from my supportive family, friends, fans, coaches, training partners, sponsors, Triathlon Australia, the ITU and many more, you all know who you are - thank you."

Anne Gripper, chief executive officer of Triathlon Australia, said: "Robbo's race record at world championships is truly exceptional and his ability to consistently win or podium in big races has made him an icon of Australian triathlon.

"Triathlon Australia congratulates him on a successful and productive elite career, wishes Robbo the very best in his journey post triathlon and hopes he has the same successes in his personal and professional life as a new chapter begins."