The 39-year-old Ukrainian, who is unbeaten in his professional career, said that he wanted "to make them free so that the guys who are in line for them can box."
Usyk's announcement came just a month after he came close to a shock upset defeat to kickboxer Rico Verhoeven.
Usyk needed a highly controversial 11th-round stoppage to turn the tables on the Dutchman, who had been leading on the scorecards up to that point despite taking part in only his second boxing bout.
"Good day to everyone. Today is Friday, the weather is good, and it's a good day to say that I want to vacate all the belts that I currently hold - to make them free so that the guys who are in line for them can box," said Usyk in a social media post.
"My friends, I'm giving up the belts, but I'm not leaving the sport, because I still have my last dance.
"I want to thank everyone; I respect all organisations. I want to thank everyone and say there is more to come."
Usyk has been an undisputed world champion at both cruiserweight and heavyweight and boasts an unblemished record of 25 victories, including 16 knockouts, in as many fights.
In his amateur career, he was an Olympic, world and European champion.
His most iconic victories have been against British heavyweights Tyson Fury, Anthony Joshua and Daniel Dubois - whom he beat twice each.
He beat Joshua in September 2021 to win the WBA, WBO and IBF belts and then took the WBC belt off Fury in May 2024.
He had to vacate the IBF belt for his rematch with Fury, but then won it back off Dubois in July 2025, only to vacate the WBO belt a few months later.
Dubois then beat fellow Briton Fabio Wardley in May to win that belt.