Anthony Joshua, 31, faced Kubrat Pulev in the heavyweight title match held at the Wembley Arena in London, the capital of England.
Within the scope of the new type of corona virus (Covid-19) outbreak measures, a thousand people were allowed to watch the encounter in the hall.
Joshua, who appeared as the superior side in the ring throughout the fight, defeated Pulev by knockout in the 9th round and managed to protect the WBA, WBO and IBF belts.
Joshua, who won 24 out of 25 games in his career, including 22 by knockout, had his only defeat against Andy Ruiz last year.
Pulev, 39, who previously lost to Ukrainian Wladimir Klitschko in 2014, suffered his second defeat in his 30th game.
With this win, Joshua is expected to face the World Boxing Council (WBC) heavyweight champion Britain’s Tyson Fury.