The South Korean-born New Zealander earned $1.2 million and became the ninth first-time winner on the tour this season.
Lee, David Hearn, Kevin Kisner and Robert Streb were tied at 13 under after four rounds on the Old White TPC course in West Virginia.
Lee and Hearn both made birdie putts on the first playoff hole on the par-3 18th, eliminating Streb and Kisner.
Hearn then drove behind a tree on the par-5 17th and made bogey. Lee reached the green in three shots and two-putted for par.