Amir Khan will earn a top-five ranking with the WBC if he overcomes Billy Dib next week.
The former world champion was due to take on Neeraj Goyat but the Indian fighter suffered head injuries in a car crash last week.
He has been replaced by Dib who operated at featherweight in his prime for the clash in Jeddah.
And victory for Khan will catapult him back into world title contention following his defeat by Terence Crawford in April.
WBC president Mauricio Sulaiman said, "The fight between Amir Khan and Billy Dib is now officially confirmed for the WBC International title and I’m proud that it will be contested for at the magnificent King Abdullah Sports City stadium in Jeddah.
"The specially commissioned WBC Pearl Championship belt that was due to be challenged for will now be contested at a future date. The winner of Khan and Dib will receive a WBC ranking in the top five of the welterweight division."
Former WBA and IBF light-welterweight champion Khan is bidding to get his boxing career back on track after he was accused of quitting against Crawford.
"We had some bad news today that Neeraj Goyat was in an accident in India," Khan told BNTV.
"He is no longer able to fight on July 12 in Saudi Arabia. We have made a change in opponent, I hope Neeraj recovers quickly and gets fully fit again.
"Things like that just happen in boxing. Our new opponent is Billy Dib, a two-time world boxing champion.
"He will be coming up to fight me like I went up to fight (Saul Alvarez) Canelo. He feels confident and he wants to fight me."
Dib, 33, a former IBO super-featherweight and IBF featherweight champion, is set to return to the ring having announced his retirement after a points defeat to Tevin Farmer in an IBF super-featherweight bout in Sydney last August.
