Anthony Joshua and Tyson Fury will contest their long-awaited all-British heavyweight fight at Cardiff's Principality Stadium on 11th December.
The bout, more than a decade in the making, will be broadcast globally on Netflix.
Organisers are considering a late start to cater for audiences in the United States.
Joshua and Fury will come face-to-face at a news conference in London on Wednesday, 30th September, as the build-up begins to one of the most anticipated fights in British boxing history.
Joshua says he is inspiring a generation while Fury is yet to comment on the announcement.
The event is being promoted as a collaboration between Saudi boxing powerbroker Turki Alalshikh's The Ring and UFC chief Dana White.
Alalshikh says two of the best heavyweights of this generation, finally in the ring together.
The former two-time world champions had already signed contracts for the bout earlier this year, but the date and venue had yet to be confirmed.
London's Wembley Stadium and New York's Madison Square Garden were the frontrunners to stage the fight, but both presented logistical issues before Cardiff recently emerged as an alternative.
The Principality Stadium has hosted late-night boxing before, including Joe Calzaghe's fight against Mikkel Kessler in November 2007.
Welsh Rugby Union and Cardiff Council officials welcomed the fight, saying it would reinforce the city's reputation for staging major events and could provide a significant economic boost, although some operational details still need to be finalised.
Joshua had been pushing for the fight to take place in the UK and has got his wish.
On 11th December, two of the biggest heavyweights of this generation finally collide and the winner will take a significant place in heavyweight history.
