The Irishman overturned a six-shot deficit in the final round of the Tour Championship to become the first player to win the FedEx Cup three times, as he admitted it eased the pain of his near miss at last months British Open at St Andrews.
McIlroy carded a closing 66 at East Lake to finish 21 under par, a shot ahead of Sungjae Im and Scottie Scheffler, who had been an odds-on favourite to secure his fifth win of the season and the 18million US dollar (£15.3million) first prize.
However, Scheffler struggled to a 73 and McIlroy took full advantage to claim an extraordinary victory, having started the week six shots behind the world number one under the handicap scoring system and making a triple bogey on his first hole.
McIlroy has now earned 43million US dollars (£36.6million) for his three FedEx Cup victories. Tiger Woods (2007, 2009) is the only other player to have won it more than once.
"To be the first to do anything in the game that you love so much, it's an incredibly proud moment," McIlroy said. "The FedExCup isn't that old. I've won three out of the 16, I guess is it now?
“To do something else that no one else has done and to even just give myself the opportunity to do that today, and then coupling that with the opportunity and playing the golf when you needed to to get the job done, incredibly satisfying.
"I've been knocking on the door so much this year. St Andrews was really hard for me. Still, it was a tough one to get over. This softens the blow a little bit. It doesn't make it that much easier to get over, but it's great to end the season on a high note like this.
"I want to say I feel like Scottie deserves at least half of this (trophy). He has had an unbelievable season. I feel sort of bad that I pipped him to the post.
“He’s a hell of a competitor, he’s an even better guy, it was an honour and a privilege to battle with him today and I’m sure we’ll have many more. I told him we’re one-all in Georgia this year; he got the Masters, I got this.
“I didn’t really give myself much of a chance teeing off today, I thought six behind was going to be really tough to make up but my good play and Scottie’s not-so-great play meant it was a ball game going into the back nine.”
Asked what it to meant to win in a season in which he has emerged as one of the PGA Tour’s biggest advocates in its battle with LIV Golf, McIlroy added: “It means an awful lot.
“I believe in the game of golf, I believe in this Tour in particular, I believe in the players on this Tour. It’s the greatest place in the world to play golf, bar none, and I’ve played all over the world.
“This is an incredibly proud moment for me but it should also be an incredibly proud moment for the PGA Tour. They have had some hard times this year but we are getting through it and that was a spectacle out there today.
“Two of the best players in the world going head to head for the biggest prize on the PGA Tour and I hope everyone at home enjoyed that.”
Scheffler was philosophical after his defeat, as he admitted he didn’t make the most of his chances as he hit a three over par final round of 73.
"I hit the ball really well today," Scheffler said. "I just for whatever reason, I couldn't get enough looks.
"Maybe if I could take a few shots back, I'd probably take back the drive on 16. That would be the one I'd like to have back.
"But outside of that, I really fought hard today. Rory [McIlroy] just played a really good round of golf. He made some key putts there at the end, and he definitely deserved to win."