Gary Woodland, Phil Mickelson and Robert Streb tied for 4th two shots from Simpson and Rodgers.
McIlroy broke the tournament apart with his course record breaking third round of 61 and from that point on it appeared the rest of the field were playing for second given the quality of McIlroy's play throughout the weekend.
Rodgers, a winner on the web.Com Tour earlier in the season, challenged briefly during the final round but three shots was the closest he could get and when he dropped three shots over the closing two holes McIlroy cruised to his 11th PGA Tour title.
Simpson, who started the day closest to the leader, had the opportunity to put pressure on McIlroy early but instead he went the other way bogeying the first and third holes and it was up to Rodgers to at least try and make a contest of it.
McIlroy, though, a winner of this event five years ago when capturing his first PGA Tour title, was never really in danger and although he bogeyed early he was soon into stride with birdies at the 5th and 7th. Three more through his back nine even allowed him the luxury of a bogey at the 17th and still a casual walk up the 18th in front of fans who he must feel a great affinity with given what this event means to him.
"Obviously I'm delighted to get the win," said the champion. "The way I played yesterday I was in control of the tournament and I just needed to shoot a solid round and that was going to get me over the line.
"It is a great momentum builder heading into the thick of the season with three majors coming up and a lot to play for. I don't think my game has been in better shape and I am excited for the next three months."
McIlroy now heads to London for the BMW PGA Championship followed by the Irish Open at Royal County Down, an event in which he has played a key role in its growing status.
Rodgers was on track to earn enough money as an invite to secure unlimited invites for the balance of the year. He needed to finish alone in second position and appeared to have that locked up until a double bogey and bogey at the 17th and 18th cost him in that regard. He finished joint runner-up and still needs another US$50,000 or so. He has starts in the next three full field events so could well get the job done but he missed a great opportunity today.
Simpson was playing in front of a home crowd and performed well at a golf club at which he is a member.
Geoff Ogilvy finished as the leading Australian on a golf course where he has often played well. A double bogey at his final hole cost Ogilvy outright 4th but he was not alone in struggling with Quail Hollow's demanding finish.
It was however Ogilvy's best finish since the Deutsche Bank Championship eight months ago and following a solid week at the Players last week is perhaps signalling better things to come.
Matt Jones was the next best of the Australians when he finished 28th.
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