Garcia, who had a one-shot lead after four holes yesterday when play was halted at Sedgefield Country Club because of rain and thunderstorms, shot a four-under 66 in the final round for an 18-under total, two shots clear of South African Tim Clark.
The Spaniard, who needed a strong result to force his way onto Europe's team for the Sept. 28-30 Ryder Cup, guaranteed a place on the squad by securing his eighth PGA Tour victory and first since the 2008 Players Championship.
"I kind of did it last year, too, in Germany when I needed to play really, really well to get into the British Open, which is my favorite tournament, and almost won there and then got myself into the British Open," Garcia told reporters.
"Now this year, here, hopefully this will secure my spot in the Ryder Cup team."
Garcia, who has played five Ryder Cups and finished on the winning team three times but missed Europe's victory at Celtic Manor in 2010, dislodged Ian Poulter from the 10th automatic spot in the biennial team competition.
In Garcia's last appearance at Greensboro, he held a share of the third-round lead only to watch it slip away into a fourth place finish.
Garcia, 32, was one-under in his final round when play was halted on the weekend but this time held his nerve mixing five birdies with two bogeys on the back nine to secure the win.
After a bogey at the par-three 12th, Garcia stepped it up a gear with four birdies over his next five holes, including three straight from the 15th before ending his round with a bogey.
"I think that that year (2009) I was pretty much in control and I lost it myself," said Garcia. "The course didn't do anything wrong to me.
"I was just trying to be confident (this time), trying to be aggressive as much as I could and believe in my ability to play."
