Fury said in a post on Instagram that he will fight Usyk for all four belts in Saudi Arabia, in what would be the first undisputed heavyweight title bout in a generation.
Fury did not disclose any further details about the fight but his promoter Frank Warren confirmed the deal had been done.
“Delighted to finally get this fight signed,” Warren said. “This is the biggest fight that could possibly be made in our sport.
“The heavyweights always spark the imagination of the fans, and I have no doubt this will be the biggest boxing event of the century.”
The date of the contest, which will take place in Riyadh, has not been announced, however.
Fury and Usyk had previously been in talks over a heavyweight showdown but discussions collapsed ahead of a proposed April bout at Wembley Stadium. Fury wrote on Instagram: “You can’t run rabbit run anymore Usyk, you’re getting it.”
Ukrainian Usyk, 36, is unbeaten in 21 fights, having last knocked out Daniel Dubois last month in Poland. The WBA, WBO, IBF and IBO champion twice defeated Fury’s British rival Anthony Joshua in title fights.
Fury has not been in action since knocking out Dereck Chisora last December, and the WBC champion, 35, is also unbeaten in 34 fights – with 33 wins and a draw.
Before meeting Usyk, Fury is set to face former UFC world heavyweight champion Francis Ngannou in a crossover fight on 28 October, but his WBC belt will not be on the line.
Britain’s Lennox Lewis was heavyweight boxing’s last undisputed champion in 1999.
Meanwhile, Amnesty International urged both Fury and Usyk to speak out on Saudi Arabia’s human rights record. The undisputed title fight will be the biggest boxing match to be held in the Kingdom.
“Ever since Anthony Joshua’s fight against Andy Ruiz in 2019 we’ve become used to these big-money bouts being hosted in Saudi Arabia, and they’re clearly part of a pattern of sportswashing where the Saudi authorities try to use sport to distract from their appalling human rights record,” said Felix Jakens of Amnesty International UK.
“Both Tyson Fury and Oleksandr Usyk should understand how they this fight will be used by the Saudi authorities to project a glitzy image of the country a world away from the dark reality of being jailed for voicing your opinion, of widespread torture, unfair trials and mass executions.
“Among many other cases, the retired Saudi teacher Mohammad bin Nasser al-Ghamdi has recently been sentenced to death for his peaceful remarks on Twitter and YouTube, and the Leeds University PhD student Salma al-Shehab is languishing in jail for daring to tweet about women’s rights in Saudi Arabia.
“We’d like to see both Tyson Fury or Oleksandr Usyk using their platforms to speak out about human rights issues in Saudi Arabia, something the entire Saudi population is unable to do without risking jail or worse.”