Pironkova worked her way through qualifying and completed a five-match run through the main draw without dropping a set. Her last three matches were against Top 10 players.
Pironkova piled up 21 break chances, finishing off three in each set. She won just 52 percent of the points on serve but also 52 percent when Kerber served.
Pironkova, a professional since 2002, had never before reached the finals of a WTA event and was 6-7 in ITF title matches.
Kerber fell to 3-6 in WTA finals. Eight of her nine title-match appearances have come since February 2012.
The first-place check of $120,000 pushed Pironkova's career earnings to more than $2.8 million. Kerber, who picked up $64,000, topped $5.5 million in her career.