MacDonald made his UFC debut on October 10, 2006, at Ortiz vs. Shamrock 3: The Final Chapter against the favored The Ultimate Fighter 3 finalist Ed Herman.

MacDonald followed up the performance with a win over The Ultimate Fighter 1 veteran Chris Leben via modified guillotine choke in the second round.

At UFC 77, MacDonald faced Yushin Okami, who was coming off a loss to Franklin in a title contention elimination bout.

MacDonald lost the fight via submission due to elbows after being dropped with a glancing left jab by Gouveia and pounded on for the stoppage.

Matchmaker Joe Silva commented that the door would be left open for MacDonald to return should he earn a few more victories in smaller promotions.

MacDonald was scheduled to face Rafael Natal on December 11, 2010, at UFC 124,[5] but pulled out of the fight after suffering an injury in training.

[6] Nearly a year after his last bout, MacDonald fought and submitted Ryan Jensen via first-round triangle choke at UFC 129 on April 30, 2011.

[7] MacDonald faced Alan Belcher on September 17, 2011 at UFC Fight Night 25, losing via verbal submission due to strikes in the first round.

He manages a number of Canadian professional MMA fighters, including Ryan Machan, Evan Sanguin, George Belanger and Derek Clark.