The Ukrainian won with the judges scoring the fight 120-108, 119-109 and 119-109
Oleksandr Usyk has become the first man to unify all four world cruiserweight titles by beating Murat Gassiev in Moscow.
The Ukrainian was awarded a unanimous victory – 120-108, 119-109, 119-109 – and his win also means Usyk wins the inaugural World Boxing Super Series Ali Trophy.
Gassiev, the Russian, held the WBA and IBF titles heading into the fight, with 31-year-old Usyk becoming the first man to unify all four world titles at that weight class, having already been WBO and WBC champion.
This bout, the World Boxing Super Series final, was originally set to take place in May, but was pushed back after Usyk suffered an elbow injury.
Dillian Whyte v Joseph Parker: Live commentary, fight date and undercard info
Anthony Joshua and Jarrell Miller square off in heated confrontation in New York
'I KNOW I'M GOOD AT THIS'
Anthony Joshua reveals how long he has left in boxing
George Groves v Callum Smith confirmed as World Boxing Super Series final
New HD footage emerges of David Haye's press conference brawl v Dereck Chisora
Who will Tony Bellew fight next? Five most likely options ranked
Anthony Joshua vs Alexander Povetkin: TV channel and ticket information
'Povetkin is a ferocious animal on drugs… but Joshua will obliterate him'
WBC confirm Lewis will come out of retirement for Klitschko and reveal date
Next Saturday sees one of the biggest fights of the year, with Dillian Whyte and Joseph Parker clashing at London’s O2 Arena.