Hahn defeated Dustin Johnson of the United States on the third playoff hole, the par-3 14th, where he drained a 23-footer for birdie to win the tournament.
Hahn, Johnson and Paul Casey of England ended the regulation at 6-under at 278.
With Sunday's victory at "the Riv," Hahn had US$1,206,000 in his pocket. The 33-year-old turned professional in 2003.