Wladimir Klitschko announces retirement from professional boxing
The 41-year-old, who retires with a professional record of 64 wins, including 53 by knockout, against 5 losses, announced his decision in a special video published on his official website.
"I have achieved everything I dreamed of, and now I want to start my second career after sports," said Klitschko.
"I would have never imagined that I would have such a long and incredibly successful boxing career," he added.
Klitschko was supposed to face Anthony Joshua in an anticipated rematch following his technical knockout defeat to the Briton at the famous Wembley Stadium in April.
Their second fight was provisionally agreed for November 11 at the T-Mobile Arena in Las Vegas.
Born in Semipalatinsk, Kazakhstan, Klitschko made his professional boxing debut in Germany in 1996, where he was based for the majority of his career.
He went on to record 24 straight wins in the space of two years, before losing for the first time, to American journeyman Ross Puritty.
He then added another 18 wins and two defeats to his record, before going undefeated for 11 years in the period from 2004 to 2015.
Klitschko lost the last two fights of his career: against Tyson Fury by unanimous decision and then to Joshua, in 2015 and 2017 respectively.
As an amateur, the Ukrainian won an Olympic gold medal at the 1996 Atlanta Summer Games, along with two gold and two silver medals at the European and World championships.