Final round leaderboard:
-15 R McIlroy (NI) -11 P Mickelson (US) -10 A Cabrera (Arg) -9 B de Jonge (Zim) -8 B Van Pelt (US) -7 R Fowler (US)
Selected others: -6 P Harrington (Ire), J Furyk (US), A Kim (US), B Mayfair (US) Level L Westwood (Eng) +1 R Fisher (Eng)
McIlroy holes a 43-putt on the 18th to the delight of the North Carolina crowd
Rory McIlroy shot a course record 62 at Quail Hollow to capture his first PGA title, and become the youngest winner on the Tour since Tiger Woods in 1996.
The Northern Irishman, who turns 21 on Tuesday, carded an eagle at 15 and eight birdies in a 10-under-par final round to win by four shots.
American Phil Mickelson finished second, a shot ahead of Angel Cabrera.
"I'm delighted - I don't think I've ever played a better round in my life," McIlroy said afterwards.
" I'm just so excited. I got off to a pretty slow start this week and had to fight to make the cut and the weekend was just very, very special."
To win at 20 is incredible. He's some kind of player
Phil Mickelson on McIlroy
He added: "I suppose I just got in the zone. I didn't realise I was going eight, nine, 10 under par. I just knew I'd got my nose in front, I was just trying to stay there.
"Ever since I was 10 or 11, I wanted to be a professional golfer and you know it's been a crazy ride to this point.
"I'm going to have a bit of a party on Tuesday night down in Sawgrass. If I was back home and had a win like this I'd be having a good one tonight."
Ireland's Padraig Harrington was joint seventh in North Carolina on six under after carding 68, where he was joined by six others, including American duo Jim Furyk and Anthony Kim.
Zimbabwean Brendon de Jonge shot a superb six-under 66 to finish fourth, a shot ahead of American Bo van Pelt, who in turn ended a shot ahead of fellow countryman Rickie Fowler.
RORY McILROY FACTFILE
1989: Born 4 May, Holywood, Northern Ireland
1991: Hits a 40-yard drive at the age of two.
1998: Makes his first hole in one
2004: Helps Europe win the Junior Ryder Cup
2007: Opening round 68, leading amateur at Open at Carnoustie
2008: Youngest player to make world's top 50
2009: Ties for third at USPGA
2010: First player since Tiger Woods to win on PGA Tour before 21st birthday
But the day was all about McIlroy, who capped his round with a superb 43-foot birdie putt on the 18th.
He began the day four shots off the lead, held then by Billy Mayfair - who shot a final round four over 76 to drop out of contention - but caught fire midway through his opening nine holes. After going to the turn in 32, including a hat-trick of birdies from the seventh, McIlroy stormed clear of the field with a brilliant run of birdie-eagle-birdie from the 14th.
The highlight of his round was a stunning 207-yard approach shot on the 15th which landed four feet from the flag, giving him the chance to convert a simple eagle putt.
He followed that with a mid-iron from a fairway bunker on the 16th to four feet for yet another birdie and, at that stage, a four-shot lead over Masters champion Mickelson.
He made par on the 17th and then capped a stunning day's work with the long putt on the 18th for a birdie.
Mickelson described McIlroy, who missed the cut in his two previous events, including the Masters at Augusta, as an "amazing talent".
He added: "To win [on the tour] at 20 is incredible. He's some kind of player."
McIlroy's only previous tournament win as a professional came at last year's Dubai Classic but Harrington predicted that he would now go from strength to strength as a result of his victory at Quail Hollow.
"There's an awful lot of pressure on him," said Harrington. "When he plays in Europe he's a big star and when you're not winning, you're not delivering, and it becomes a burden. It's amazing the difference when you get a win.
"He will be a lot more comfortable with who he is, a lot more patient."