The second-seeded Bouchard, who had not lost a set on the way to her second career final, held her nerve in the third set after five breaks of serve in a row to win in 1 hour, 53 minutes.
"She's a great player, and she can be very dangerous at times, so I'm really glad I stayed with it and kept fighting for it during the third set," Bouchard said.
The 20-year-old Bouchard had won the only previous matchup between the pair in the first round of the U.S. Open last year.
"This is kind of like a stepping stone for me. Winning a WTA title is of course a goal I've had, and I'm so happy to accomplish it, but I still want to achieve more -- more titles, bigger titles," Bouchard said.