Stosur, ranked 15th in the world, broke Schiavone to go up 3-1 in the second set and dominated the fourth-seeded player the rest of the way to close out the match in 1 hour, 8 minutes.
Stosur 25, defeated top-seeded Caroline Wozniacki of Denmark on Saturday to advance to the final of the $220,000 tournament.
Stosur has won her last four of five matches against Schiavone, all in straight sets. Two of those wins came this year, with the Australian winning 6-1, 6-4 at Indian Wells and 6-4, 6-2 at the French Open.
It was Stosur's first title victory in six WTA tournament finals. She has won 22 doubles titles and four ITF titles. Prior to Sunday's win, the Australian's best result this year was runner-up at Los Angeles in August to Ana Ivanovic of Serbia.
Schiavone has claimed one win from 11 tournament finals.
Top seeds Chuang Chia-jung of Taiwan and America's Lisa Raymond won the doubles title with a 6-2, 6-4 win over unseeded pairing Chanelle Scheepers of South Africa and Abigail Spears of the United States.