UFC officials announced the welterweight contest Thursday. The event will take place at Halifax Metro Centre and air on Fox Sports.
MacDonald (17-2) will look to potentially solidify a UFC title shot against Saffiedine. The 25-year-old Canadian is 8-2 in the UFC and coming off a dominant unanimous decision win over Tyron Woodley at UFC 174 in June.
Saffiedine (15-3) scored his first UFC victory in a unanimous decision against Hyun Gyu Lim at a UFC Fight Night in January. He was scheduled to fight Jake Ellenberger at UFC 172 in April, but was forced from the card due to injury.
A former Strikeforce champion, Saffiedine will ride a five-fight win streak into the contest. All five wins have come via decision.
ESPN.com ranks MacDonald and Saffiedine the Nos. 3 and 10 welterweights in the world, respectively.
The 170-pound main event is currently the only fight scheduled for the Oct. 4 card. It will mark the UFC's first trip to Halifax.