The American was the first to falter at the first extra hole with a drive into the rough and a wayward second shot, before Garcia and Singh both sunk mammoth birdie putts to force a second extra hole.
And it all went wrong for Garcia who drove into the rough before planting his second shot behind a tree, while Singh reached the green in two.
The three-time major winner had two putts for glory and made no mistake, landing his second win following success at the WGC-Bridgestone Invitational at the start of the month.
"It was pretty close all day," Singh said. "And nobody had a two-shot lead at any point. It was either seven under or eight under or six under.
"It wasn't easy to get close to the hole, so birdie was difficult to come by. It was drying out a lot and you've got to play conservative on some holes.
"It was a tough day, but it was a great play-off - I enjoyed that."
England's Paul Casey had been one shot off the lead in joint-second overnight but could only manage a one-over 72 to slip back to a share of seventh at -6.



