McIlroy collected his second major title with the win, which earned him the world No. 1 ranking.
His total of 13-under 275 was eight better than runner-up David Lynn, who shot a 68 to finish at minus-5. McIlroy's margin broke the old mark for one-sided wins at the PGA Championship -- a 7-shot triumph turned in by Jack Nicklaus in 1980.
Second round co-leader Tiger Woods fell into an 11th-place tie at minus-2 with an even-par 72 in the final round.
Members of Congress to keep receiving porn magazine
Rosie O'Donnell unveils nearly 50-pound weight loss