Vitaly Klitschko has vacated his WBC belt but was named champion emeritus on Monday, leaving the door open for the leading Ukraine politician to one day return to the ring.
Klitschko, the reigning World Boxing Council champion, is unlikely to box again as he joins thousands of protesters in weeks-long demonstrations against the government in Kiev.
"I thank the WBC and its president Jose Sulaiman for the support in our battle for democracy and freedom in Ukraine," Klitschko said in a statement.
"The WBC offer gives me the theoretical possibility to return to the ring but that is something I currently cannot imagine. My focus is on politics in Ukraine and I feel the people there need me."
The 42-year-old has won 45 fights with 41 of them knockouts and has only lost twice. His most recent fight dates back to September 2012 against Manuel Charr and he has long contemplated retiring from the sport.
His younger brother Vladimir holds all the other major world heavyweight titles.
"My brother will take care of the sporting success and I will support him in that as he has supported me in my fight in Ukraine," Klitschko said.