The 32-year-old confirmed the news on an Instagram post as he thanked his wife, fellow Olympic cyclist Melissa (nee Hoskins).

Dennis, one of Australia's most decorated cyclists over the past decade, is in his second season with the powerful Jumbo-Visma team.

The Adelaide rider won the 2018 and '19 world time trial championships after several near-misses.

He won bronze in the discipline at the 2021 Tokyo Olympics after taking silver on the track in the team pursuit at the 2012 London Games.

Dennis broke the prestigious hour record on the track in 2015, riding 52.491km, and held it for three months until British rider Alex Dowsett bettered his mark.

The same year he also set the unofficial record for the fastest Tour de France stage - clocking 55.446km/h to win the prologue stage.

That also made him the most recent of only seven Australians to have worn the yellow jersey as the Tour leader.

He was named the 2015 Australian cyclist of the year.

Dennis then tried to develop into a Grand Tour contender, following the example set by fellow pursuit and time trial ace Brad Wiggins from England, but eventually abandoned the project.

"Thank you @melissamdennis for supporting me throughout my entire professional career, all while raising two of the best kids I could ever ask for," Dennis has posted.

"Cycling, you have given me a lot and I'll be forever grateful. It is still a long season ahead however it will definitely be my last as a professional."

Dennis' most recent win was stage two of last month's Tour Down Under in his home town, which also put him into the leaders' ochre jersey until eventual winner and compatriot Jay Vine took it a day later.

While Dennis has enjoyed an outstanding career, he also at times has had what former teammate Tejay Van Garderen once teasingly called a "filthy mouth ... (and) short temper".

But his popularity was underscored by a number of tributes from fellow cyclists, including Australian stars Anna Meares and Richie Porte.

"What a career Rohan. One of the most loyal and talented bike riders. Looking forward to our catch-ups post cycling," Porte replied to Dennis' Instagram post.

Australian Associated Press