It was not quite the procession everyone thought it would be. Sergio Garcia made sure of that with a six-under 66, while Rickie Fowler added to his ever-growing status as one of sport's hottest talents with a 67 to tie the Spaniard at 15-under.
McIlroy's six-shot lead he started the day with was enough of a cushion to allow himself a stumble or two in a one-under 71 before lifting his first Claret Jug in front of the thousands crammed around Royal Liverpool's magnificent grandstand arena at the 18th.
At 25 years and 77 days, he joins Jack Nicklaus and Tiger Woods as the three youngest players to win three of the four major championships.
But perhaps most poignantly, he becomes the first European player to achieve the feat. Not even Sir Nick Faldo or the late, great Seve Ballesteros managed it.