Carin Koch, who shared the lead with Becky Morgan entering the final round, posted a 4-under 68 to take second place at 11-under-par 277. Morgan closed with a 70 to take third place at minus-9.
Sorenstam opened her round with three straight pars before dropping in an eagle putt at the par-5 fourth. She came back with a birdie at the sixth to make the turn in 33.
The women's world No. 1 birdied the 11th and came right back with a birdie at the 12th to get to 11 under. Sorenstam then rolled home birdies at the 13th and 15th to establish a new course record of 64.
'I'm very happy and I thought it was amazing to come out today and play the way I did,' Sorenstam said. 'I really don't know where I got the energy from, but I couldn't ask for a better day at home and in front of my home crowd. It's very special.'
Janice Moodie matched Koch's 68 to finish in fourth place at 8-under-par 280. Stephanie Arricau was one stroke further back at minus-7 after closing with a round of 68.