Overnight leader Jon Rahm won the event but McIlroy's fourth place was enough to earn him the Harry Vardon Trophy for the fourth time in his career – and first since 2015.

McIlroy finished the season top of the European rankings after Matt Fitzpatrick, his only rival, blew up around the turn.

June's U.S. Open champion needed to win and McIlroy to not finish runner-up, or to finish second and the Northern Irishman to be outside the top seven.

But neither of those scenarios transpired as the Sheffield golfer, three off the lead playing the 8th, double-bogeyed and then dropped another shot at the 10th to end his chances.

McIlroy did not need any of the fireworks of the previous day, when he powered himself into contention with a 65, and while he could have tied Rahm on 20-under had he eagled the last he could only manage par for a 68 which included six birdies and four bogeys to finish fourth.

"It has taken me seven years to get my hands back on this trophy again; it's been eight years since I won a major. If I can keep playing the way I'm playing and keep these consistent levels up I will do that." - Rory McIlroy.

Rahm finished two shots clear of England's Tyrrell Hatton and Sweden's Alex Noren.

It was the Spaniard's his third win in six years at Jumeirah Golf Estates and worth $US3million ($A4.5m)

"It means a lot. It's been seven years since I've last done it. I've won three FedExCups since I last won," said McIlroy.

"I was a model of consistency throughout the year and I think my worst finish in European Tour events was 12th at the start of the year in Abu Dhabi.

Having achieved such consistency McIlroy will again turn his attention to ending an eight-year major drought.

"I'm really proud of my year and I am looking forward to 2023," he added.

"It has taken me seven years to get my hands back on this trophy again; it's been eight years since I won a major.

"If I can keep playing the way I'm playing and keep these consistent levels up I will do that."

Rahm began the final day with a one-shot lead and opened with two successive birdies to double his advantage and played solidly thereafter to finish with a 67.

Australia Min Woo Lee carded 69 to finish on seven-under in equal 12th.