Singh knocked in a putt from about 2 feet after a nearly perfect approach on the 18th hole at Exmoor Country Club. He gave an understated fist pump as the ball fell in, giving him his first major title on the PGA Tour Champions.
Singh (67) and Maggert (68) finished at 20-under 268. Brandt Jobe (66) was two strokes behind, while Jerry Kelly (64) and defending champion Scott McCarron (71) finished at 17 under.
Maggert had chances to win in regulation and on the first playoff hole but missed birdie putts both times.
Lone Oak alum Kenny Perry shot a final round 68 and finished tied for 16th.
