Bradley went to the 16th hole on Sunday down by five strokes, but he made two straight birdies and Dufner bogeyed three holes in a row to leave them tied at 8-under 272.
In the playoff, Bradley made a four-foot birdie at the 16th hole to gain the upper hand. Dufner nearly holed out from the fairway, but missed a six-foot birdie try.
Bradley was in command by two shots when Dufner three-putted the 17th for a bogey. Dufner made birdie at the tough finishing hole but it wasn't enough. Bradley tapped in from a foot away to claim the Wanamaker Trophy by a single stroke.
Bradley graduated from Hopkinton High School in 2004.