The fight will take place on August 14 "100 per cent" Tyson said in a video posted on Twitter.
The pair will contest all four world heavyweight titles for the first time in the sport's history.
32-year-old Fury said: "I have got some massive news. I have just got off the phone with Prince Khalid of Saudi Arabia and he told me this fight is 100 per cent on, August 14."
The WBC champion, added: "All eyes of the world will be on the Kingdom of Saudi Arabia.
"I cannot wait, I repeat, cannot wait to smash Anthony Joshua on the biggest stage of all-time.
"This is going to be the biggest sporting event ever to grace the planet Earth. Do not miss it."
Joshua, a year younger than Fury, holds the WBA, WBO and IBF belts.
Plans for a fight between the pair were set in motion when Fury defeated Deontay Wilder to capture the WBC title in February last year, just a couple of months after Joshua avenged his only career loss to Andy Ruiz Jr.
Joshua retained his three belts last December with a ninth-round knockout of mandatory challenger Kubrat Pulev but the unbeaten Fury’s planned trilogy fight against Wilder has failed to materialise.
A proposed homecoming against Agit Kabayel in December was scotched, meaning Fury, who proclaims himself as the lineal champion in the division, has not fought in more than 12 months since stopping Wilder in Las Vegas.