"Yes, I've made a decision, it's time to go and pursue other things in life," Popov, considered by many one of the greatest swimmers of all time, told Reuters.
The 33-year-old, who now lives in Switzerland, was in Moscow to attend the Olympic gala in honour of IOC vice-president Vitaly Smirnov, who turned 70 on Monday.
As a 20-year-old Popov won a historic 50 and 100 metres freestyle double at the 1992 Barcelona Olympics before repeating the feat at the Atlanta Games four years later.
The Russian finished second behind Dutchman Pieter van den Hoogenband in the 100 freestyle at the 2000 Sydney Olympics but reclaimed the title of being the world's fastest swimmer by winning the 100 at the 2003 world championships in Barcelona, becoming the oldest world champion at age 31.
He still holds the world record for the 50 metres freestyle -- 21.64 seconds, set in 2000.
His last competition, however, ended in a disappointment when he failed to make a final at either the 50 or the 100 freestyle at last year's Athens Olympics.
"I've had it all, triumphs, disappointments, great rivalries over the years and it's time to say goodbye," said Popov, who also overcame a life-threatening stabbing on a Moscow street shortly after the Atlanta Olympics.
Popov, who returned to Europe in 2003 after 10 years in Australia and now lives in the small Swiss town of Bienne with his wife Daria and two children, said he has several options for the future.
"I'm a worldwide ambassador for Omega (watches) and I still have my IOC duties," said Popov, who is on the IOC's athletic commission. "I also would like to help younger swimmers but I haven't had any offers so far, at least here in Russia."