Lee, an 18-year-old Korean, played the final round at Stonelick Hills without a bogey. She finished three rounds at 15-under 201 for a three-shot win over two players.
The $14,000 first-place check more than doubled her rookie season earnings to $25,277 in nine events. Her previous best finish was a tie for third place at the Louisiana Pelican Classic.
Violeta Retamoza, who shared the overnight lead with Lee, had an even-par 72 Sunday and shared second place with Eunjung Yi (69) at 12-under 204. It was Retamoza's second runner-up finish of the season.
Mollie Fankhauser fired a 9-under 63 to climb from a tie for 33rd place overnight into fourth place alone at 10-under 206. Cortney Reno (69) was another shot further back at 207.