Tyson Fury and Oleksandr Usyk will fight for the undisputed heavyweight title on 17 February in Saudi Arabia.
Briton Fury, 35, is the WBC champion with Ukraine's Usyk, 36, holding the WBA, WBO and IBF belts.
The winner in Riyadh will become the first undisputed heavyweight champion since 1999.
The bout was scheduled to take place on 23 December but Fury's difficult encounter with Francis Ngannou last month derailed those plans.
Instead on that date, in Riyadh, former heavyweight world champions Anthony Joshua and Deontay Wilder will fight separate opponents.
Should Joshua overcome Otto Wallin and American Wilder beats former champion Joseph Parker, the pair could fight each other in 2024.
Fury has won 34 fights with one draw since turning professional in 2008.
He has faced criticism for failing to reach terms with Usyk after a proposed bout at London's Wembley Stadium in April fell through.
An unexpected announcement in September confirmed a deal had been brokered by Turki Alalshikh, of Saudi Arabia's General Entertainment Authority.
Fury had been expected to cruise past former MMA champion Ngannou - making his boxing debut - in a non-title fight, but narrowly edged a split-decision success.
The Morecambe fighter and Usyk came face-to-face following the victory, but after the fight Fury and his co-promoter, Frank Warren, suggested it would be pushed back to 2024.
The last undisputed heavyweight champion was Briton Lennox Lewis, who beat Evander Holyfield in Las Vegas to defend the WBA, WBC and IBF titles.
No heavyweight has held all four of the recognised world titles.
The contest will form part of 'Riyadh Season' - an entertainment events festival held in Saudi Arabia's capital every winter since its launch in 2019 and was kicked off this year by the Fury-Ngannou clash.
A number of high-profile bouts have been held in Saudi in recent years, including Usyk's win over Anthony Joshua in August 2022.
The Gulf kingdom has been accused of investing in sport and using high-profile events to improve its international reputation.
Saudi Arabia has been criticised for its human rights violations - 81 men were executed on one day last year - women's rights abuses, the criminalisation of homosexuality, the restriction of free speech and the war in Yemen.
Its international standing was severely damaged by the 2018 killing of Jamal Khashoggi, a US-based Saudi journalist who was a prominent critic of the government.
Human rights campaigners say sport is being used by the Saudi government to distract from long-standing reputation issues.
Felix Jakens, Amnesty International UK's Head of Priority Campaigns and Individuals at Risk, said in a statement: "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.
"They are clearly part of a pattern of sportswashing where the Saudi authorities try to use sport to distract from their appalling human rights record.
"We'd like to see both Tyson Fury or Oleksandr Usyk using their platforms to speak out about human rights issues in Saudi Arabia."
Analysis - Fury can silence naysayers with historic win
History will be made on 17 February in Riyadh.
Never has there been a four-belt heavyweight undisputed world champion.
Fury and Usyk have sat firmly at the top of the division ever since the Ukrainian dethroned Joshua. The winner will now cement their legacy as the greatest of their generation.
Some fans feel Fury's below-par performance against Ngannou has devalued the undisputed contest. It was worse than a bad day at the office - edging a split decision against a debutant may well be a sackable offence.
There were calls for a Fury-Ngannou rematch but with mandatory challengers for Usyk's belt waiting in line, the chance for an undisputed bout, with all the belts on the line, may not have come again.
Fury will have a point to prove and naysayers to silence, while there are perhaps some question marks about Usyk too.
Up until a few weeks ago, Fury was probably the favourite. Usyk is not considered a natural heavyweight and the thinking was Fury would, quite simply, be too big and too strong.
The two will come face-to-face at an intriguing news conference in London on Thursday.
Has the Ngannou performance humbled the usually brash Fury? You never quite know how he will act, but you are pretty much guaranteed box-office entertainment from the Gypsy King.
