Usyk, 34, has never fought for a heavyweight title but has held the IBF, WBA, WBO and WBC titles at cruiserweight, the division below heavyweight.
Joshua is the current defending champion of the IBF, WBA and WBO belts and will put these at risk as he takes on Usyk.
So, when will they fight, where will the event take place and will there be spectator tickets available? This is what you need to know.
When and where is the Joshua v Usyk fight?
Anthony Joshua's world heavyweight title defence against Oleksandr Usyk will take place at Tottenham Hotspur Stadium on 25 September.
The stadium is located in North London and holds around 60,000 spectators.
Can I get tickets for the Joshua v Usyk fight?
The fight will be watched by spectators, though the current number of spectators has yet to be confirmed.
The lack of clarification comes as PM Boris Johnson announced that major events (attended by more than 20,000) will require spectators to show a ‘vaccine passport,’ confirming they have had two Covid vaccines.
The new rules are expected to be brought into effect in late September, but there has yet to be distinct guidelines to support the vaccine passport rules.
Following the announcement of the fight, 31-year-old Joshua said: "We are two Olympic gold medallists who have fought our way to the top and never avoided challenges," Joshua said.
"The venue is exceptional, the atmosphere will be electric, I'm honoured to be the first person to fight in such an awe-inspiring venue. The stage is set and I am ready to handle business."
Where can I buy Joshua v Usyk tickets?
Tickets for the Joshua vs Usyk fight will go on sale from midday on Tuesday 3 August.
Tickets are priced £40, £60, £80, £100, £150, £200, £400, £600 and £2000. Access ticketing can be purchased via Tottenham Hotspur by calling +44 344 844 0102, pressing option 1 then 5 from midday on 3 August.
Matchroom Fight Pass members will be able to purchase tickets via StubHub using a priority ticket code from midday on Monday 2 August.
Will the fight be on TV?
The fight will be aired live on Sky Sports Box Office, with the ring walk expected to take place at around 10pm.
Watching the fight is likely to cost viewers £19.99.
Why is Usyk challenging Joshua?
Originally Joshua was preparing to take on Tyson Fury, in a highly competitive and explosive ultimate World Championship fight in Saudi Arabia.
In mid-April, Fury’s promoter Eddie Hearn confirmed the fight was set to go ahead and both were in preparation for the event.
However, Fury was ordered by an independent adjudicator to fight American Deontay Wilder, who argued he was legally bound to a re-match of their February 2020 bout. Fury won the fight, making him the two-time world heavyweight champion.
Fury and Wilder will now fight in Las Vegas on 9 October, but Joshua was unimpressed by the cancellation of his meeting with Fury.
When the Joshua v Fury fight failed to materialise, Joshua called Fury "a fraud".
Now, he will face Usyk, who is the former undisputed world cruiserweight champion with 18 wins in 18 fights.