The German, ranked 20th in the world, saw off her American opponent 6-3 6-3 in Austria on Sunday.
"It's a super feeling, I am totally happy," Petkovic is quoted as saying by Associated Press.
"I want to get back into the top 10 and I am just playing good tennis. My serve and my footwork can still improve but I am playing well."
Petkovic's first title of the year came at the Family Circle Cup in Charleston three months ago.