PARIS • Michael Phelps, the most decorated Olympian of all time, will be at the 2020 Games in Tokyo - but as an entrepreneur, selling his own brand of swimwear and not competing in the pool.

The legendary American swimmer, who has captured a record 28 Olympic medals (23 golds), retired after the 2016 Rio Games.

Now he has set his sights on success as a businessman, hoping to see the stars of the 2020 Olympics and beyond opt for his swimwear in what is a cut-throat commercial environment.

"I am finished (as a competitor)," the 31-year-old said on Thursday in Paris, where he was launching his designs.

In a partnership with US manufacturer Aqua Sphere, which started in 2014, he said that he felt reinvigorated by his new career.

"It has become a passion in which I invest a lot of time and energy. I enjoy being around sports and swimming. It will be like this for the rest of my life and I love that," he said.

In Rio, Phelps swam in his own self-designed gear as he won five more golds and a silver medal to confirm his status as a legend of the Olympics.

"I was more confident in my swimming by wearing my own gear," he explained, having originally retired from competitive swimming after the 2012 London Olympics.

His 20 years' experience in the sport will be key to business success, he added.

"I sit around a table and have meetings with designers and engineers - it's a crazy experience," Phelps said.

"I didn't have this possibility before of someone listening to what I have to say about a product."

Phelps claims that some of Australia's highly rated swimmers were interested in his designs last year but were unable to use them, so as to avoid a conflict of interest with an existing sponsor.

"Technology and sport will continue to grow," added the American. "For me the dream will become the reality by having some of the best swimmers in the world wearing our suits."

AGENCE FRANCE-PRESSE