The 26-year-old won 6-3 6-3 at the WTA International clay-court event in Bad Gastein on Sunday after breaking her opponent six times in the match.
In the first meeting between the pair, American qualifier Rogers struggled to find the momentum that had seen her beat Sara Errani, Camila Giorgi and Carla Suarez Navarro in previous rounds, and she had no answer to Petkovic's power.
The German won 82 per cent of points on her first serve in the opening set and, with two breaks, she moved ahead in the match after only 38 minutes.
Any fight Rogers had seemed to ebb away after that disappointment and she lost the opening three games of the second set.
With an uphill challenge ahead of her the world number 147 was able to come back to 3-2 only for Petkovic to turn the screw and secure the title.
The world number 20 converted 50 per cent of the break points she created, while the American's six double faults also aided Petkovic's cause.
After only 73 minutes on court in Austria the fourth seed was celebrating her second win at the tournament, having previously been crowned champion in 2009.