The pair will put the full set of belts on the line on February 17 in Riyadh, as the sport gets one man at the top of the heavyweight division for the first time since Lennox Lewis in 1999.
Usyk holds the WBA, WBO and IBF titles, as he has done since beating Anthony Joshua twice, while Fury brings the WBC belt to what has been a long-awaited bout.
A proposed date in April at Wembley Stadium fell through, but December 23 in Saudi Arabia then became the focus. However, Tyson Fury's unexpectedly bruising win over Francis Ngannou last month has pushed the undisputed fight into next year, with Anthony Joshua and Deontay Wilder among those fighting on that pre-Christmas date instead.
Despite his troubles against Ngannou, a man who was making his professional boxing debut, Fury was in typically confident mood at a press conference in London on Thursday to officially announce the bout with Usyk.
"I've got nothing to really fear with Oleksandr," Fury said.
"Maybe a graze on the face or a busted nose or something. He ain't going to do much to me, is he? I think even if he had a baseball bat in one hand and a meat cleaver in the other, he couldn't really do much to me. I'd still beat him."
Usyk was met with a barrage of insults, with Fury himself admitting at one point he was "getting a little bit carried away here" as he shouted "sausage, ugly little man, rabbit" across the table.
When the focus does eventually shift to matters in the ring, Fury is likely to come in 50lbs heavier, but he was keen to point out that size will not be the only significant factor on the night.
"There's only one winner," he said.
"I'm destined to become the undisputed champion and more than that, I'm destined to cement my legacy as the number one fighter of this era. To do that, I've got to beat this little man.
"Never mind the size. He's a middleweight. It's not the size of the dog in the fight, it's the size of the fight in the dog. He's got a big fight inside of him, but when you meet a big man who's a lot bigger than you and he's also got the fight inside, let's put it in a nutshell: You're f*****."
Asked whether this was the toughest test of his career, Fury added: "Nowhere near. Easy fight. Nowhere near the biggest threat."
Usyk cut a relaxed figure, often smiling as Fury embarked on his monologues, and he had little interest in responding when accused of quitting against Daniel Dubois in his last fight.
The Ukrainian won that bout, but it was a decision that Dubois' team appealed after the British heavyweight dropped Usyk, who was allowed four minutes to then recover, with a body shot that was deemed to be a low blow.
That was far from Usyk's best performance, as was the case for Fury when many believes he was fortunate to be handed a points victory over Ngannou, but the former undisputed cruiserweight champion is expecting a much-improved opponent in three months' time.
"I know Tyson Fury next fight will be different," Usyk said.
"I think Tyson Fury was not serious in that fight. 'It's an MMA guy, blah blah blah, I [will] win, I'm world champion'."
Summing up his approach at the press conference, he declared: "I'm very happy to be here, thank you so much everybody. I speak more in the ring."