Garcia, the No. 3 player in the world, sank a 15-foot birdie putt from the back fringe of the 18th green to win for the second time in three events and deliver Wilson his fourth career playoff loss.
Wilson, ranked No. 56 in the world, has likely earned enough points in the Official World Golf Ranking to move into the top 50 and closer to an invitation into the 2009 Masters Tournament -- a goal the Englishman and recent Augusta resident has openly referred to as "massive for me."
"It's my second home. I want to be there," Wilson said in September.
The world-class field included seven of the world's top eight players.
Wilson outplayed his playing partner, defending champion and world No. 2 Phil Mickelson, in the final round, but rounds of 67-68-69-70 weren't enough to finish off No. 3 Garcia after the Spaniard birdied the last hole of regulation to force a playoff.
Wilson, who had to sink a 10-footer of his own for par to get into the playoff, had a chance to win on the first playoff hole, but his 15-foot uphill birdie putt was short.
Twice his approach shots on the par-5 18th hole in the playoff hit within a few feet of the cup and spun back down the slope into the same spot. Wilson's birdie chance on the second playoff hole just slipped over the edge of the cup.
After sleeping on the 54-hole lead, Wilson found himself in a fight atop the leaderboard that included Mickelson and Padraig Harrington. By the time Wilson made the turn, he was in a four-way tie with Garcia, Geoff Ogilvy and Peter Hanson at 12-under. When Garcia and Hanson went a shot up playing in front of him, Wilson answered with an extraordinary string of putts, starting at No. 14.
He drained a 25-footer for birdie for the par-5 14th to rejoin the lead; a 20-footer to save par on 15; and an 8-footer for birdie on 16 to take the lead alone. Then, he got up and down from a bunker on 17 to take his narrow lead to the 18th hole, where Garcia ultimately tied him to force the playoff.