The 'Rage on the Red Sea' will take place at the Jeddah Super Dome and will see Joshua look to avenge his defeat to Usyk last September - which cost him the WBA, IBF and WBO heavyweight belts.
The fight had appeared in doubt as Usyk was in his native Ukraine helping the war effort against Russia but the champion was allowed to leave the country in March to train for the world title bout.
Usyk said: "I have a goal, with the help of the Lord I will complete my mission."
Joshua is relishing the chance to become a three-time heavyweight world champion and described the clash as "my date with history".
The Brit said: "Fighting championship level back to back has had its pros and cons, but I decide every day to get stronger, to learn from my experiences and grow. A happy fighter is a dangerous fighter and I am the happiest and most motivated I have been."
The decision to hold sporting events in Saudi Arabia has proved controversial due to the nation's poor human rights record and the country has been accused of 'sportswashing' to enhance its image.
Joshua's promoter Eddie Hearn has rejected concerns about the venue and feels that the financial package offered is the best for the competitors.
He said: "The sportswashing thing is something over my head.
"Our job is to provide opportunities to the fighters. If I put a proposal in front of Joshua and he said to me he was going to Saudi Arabia, and I advised him against it, he would say 'see ya'."