The fight has been confirmed to take place at Tottenham Hotspur Stadium on 25 September.
31-year-old Joshua will be risking his IBF, WBA and WBO belts against the Ukrainian, who is his mandatory challenger.
Usyk, 34, has not fought for a title as a heavyweight but held all four belts a division lower at cruiserweight.
Joshua was ordered to defend his WBO title after the collapse of his bout with fellow Briton Tyson Fury.
“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.”
Meanwhile, Fury will be facing Deontay Wilder for the third time in October.