And he will face a possible penalty from the PGA Tour for failing to play enough events this year as part of its field enhancement criteria.
He was steady throughout the cold and drizzly final round and had a one-stroke lead when he got to the 18th tee. That put him in violation of a new PGA Tour rule created to route big-name players to smaller events.
Spieth began the year ranked second in the world but has dropped to 10th after failing to win and posting just five top-10 finishes.
"A lot of hard work I've done with my coach Grant (Field) is paying off at the right time of the season".
Rose lost a playoff against American Keegan Bradley in suburban Philadelphia.
He and Bradley finished on 20 under par after a rain-delayed final round and the 2011 US PGA champion required just one extra hole to seal victory.
The pair finished one shot ahead of Xander Schauffele (67) and Billy Horschel (64).
Tiger Woods ties course record with opening round 62 — BMW Championship
How fun was that? "I've hit hundreds of millions of putts with that thing". "I mean, Tony obviously is the guy right now". McIlroy had been a shot clear of Woods at nine-under par after 15 holes when Woods headed for the clubhouse.
Tiger Woods is building momentum, putting out his best showing at the 2018 Northern Trust on Saturday with a three-under 68 in the third round. I talked to the Tour a little while back and I didn't really think much of it. "It is the stuff of boyhood dreams", he said, his smile widening by the second.
Rose looks to the heavens in acknowledgement of his deceased father after winning the 2013 US Open at Merion Golf Club.
"It's not the way I have normally started the playoffs but I'm still in a good position and, mathematically, everyone at the Tour Championships can win the FedExCup", Day said.
Spieth and Emiliano Grillo were the only two players who fell out of the top 30.
The top 30 on a season-long points list advance to the Tour Championship in Atlanta starting on Thursday week. This year he did not add a new event, and the Ryder Cup - which counts - will give him just 24.
Jordan Spieth insisted he will accept his punishment from the PGA Tour if they decide he has breached regulations by failing to play in the required number of tournaments this season.