The seventh-seeded Romanian had six aces and broke serve for a 2-0 lead in the second set. She held off two break points in the final game before closing out the match with two forehand winners. It's her first win in four career finals.
Petkovic, a German wild card, played in her first final in more than 20 months after a series of injuries. She was seeking her third title.
A former top-10 player, Petkovic is pleased with her resurgence.
"Simona played incredibly, and I was a little tired," Petkovic said. "Still, I had a good week."