Britain's Fury is the WBC world champion while Ukrainian Usyk holds the WBA, WBO, IBF and IBO belts. Both have unbeaten records.
Contracts were signed in September for a proposed December 23rd date, although that was never confirmed and slid after Fury's near defeat to former UFC champion Francis Ngannou in a non-title bout in Saudi Arabia on October 28th.
Heavyweight boxing's last undisputed world champion was Britain's Lennox Lewis in 1999.