He finished on 20-under 268 at Jumeirah Golf Estates.
McIlroy now has gone eight years since his last major — he finished in the top 8 in all four majors this year — but won the FedEx Cup and its $18 million bonus, along with the Canadian Open and the CJ Cup in South Carolina.
Along the way, he returned to No. 1 in the world.
“I think my goal has been to just become a more complete golfer and I feel like I’m on the journey to doing that,” McIlroy said. “I’m as complete a golfer as I feel like I’ve ever been, and hopefully I can continue on that path.”
McIlroy's main challenge in the DP World rankings came from Matt Fitzpatrick, whose bid for the Harry Vardon Trophy blew up around the turn.
The 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. Neither of those scenarios transpired as Fitzpatrick, three off the lead, took double bogey on No. 8 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. He could have tied Rahm with an eagle on the par-5 18th but had to settle for par and a 68.
“It means a lot. It’s been seven years since I’ve last done it. I’ve won three FedEx Cups since I last won,” McIlroy, who won the FedEx Cup in August, told Sky Sports television.
“It would have been nice to get one win in there at the end of the year but Jon played an incredible tournament and fully deserved it.”
Henrik Stenson in 2013 is the only other player to win the FedEx Cup and the Europe's points list in the same year.
Rahm, who became the first player to win the tournament three times, began the final day with a one-shot lead and quickly doubled his advantage.
Fitzpatrick’s 28-foot birdie at the third got him to 15 under and within two but things started to unravel with a bogey at the short sixth and even though he immediately clawed back that dropped shot, the calamitous eighth ultimately did for his hopes.
His drive landed in a deep rut in a waste area, his next shot failed to clear the rough and having flown the green, he duffed his chip and two-putted from the fringe for a 6. That put him five behind and after missing the fairway at the 10th that led to bogey, his challenge was over.
The only trouble McIlroy, who had three birdies and a bogey in his first four holes, had at the eighth came from the flagstick which kept out his 56-foot birdie effort. He three-putted the ninth green but was not the only one as Hatton did the same for his only bogey in a round of 66.
Noren closed with a 67 and his tie for second should move him just outside the top 40, likely to secure a spot in the top 50 by the end of the year for a Masters invitation.
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