Sorenstam had 10 birdies in a bogey-free round, making the last on a 35-foot putt from the fringe at the 18th green to finish off a 10-under 62. She ended at 19-under-par 269 to win by two shots over Cristie Kerr.
Playing in this event for the first time in five years, Sorenstam equaled the course record previously held by three other players.
She also had her best round since shooting 62 in the first round of the 2003 Kellogg-Keebler Classic, which she went on to win.
'I knew I had to go low,' said Sorenstam, who also has rounds of 59 and 61 in her career. 'I was chasing some great players.'
Sorenstam collected two separate checks: $195,000 for winning the tournament and $250,000 for claiming the State Farm LPGA Series, a bonus pool check awarded to the best finisher in a seven-tournament series.
'I'm a little overwhelmed,' she said. 'I played well today, but I didn't expect all of this.'
Sorenstam began the day five shots off Maria Hjorth's third-round lead and started with a bang by making birdies on four of her first five holes -- a stretch that put her at 13-under around the turn.
She tied Hjorth at 16-under after making birdies at 11, 12 and 14 -- the last two coming on a great bunker save at the 12th and a 14-foot putt at the 14th.
Then, at the 15th, Sorenstam lagged an eagle putt within three feet to set up a birdie that gave her a one-shot lead on Hjorth.
Hjorth tied her again with a birdie at the 15th, but Sorenstam finished with two birdies to take a two-shot lead -- first draining an 18-foot birdie putt at the 17th, then rolling in a no-doubt-about-it, 35-footer at the 18th.
'It doesn't get much better than that,' Sorenstam said of finishing birdie-birdie.
Two threesomes remained on the course, but no one caught fire.
Unlike what happened in 2001, the last time Sorenstam played this event, when she carried a lead into the final round only to be defeated by Kate Golden, who shot a 63.
This time, it was Sorenstam who charged back with the low score -- her first sub-68 round since early June, when she bookended a second-round 69 at the ShopRite Classic with rounds of 64 and 67 to finish tied for second.
Sorenstam admitted, even with her 62, that she was surprised to win.
'I mean, I did play well today,' she said, 'but there was so many great players ahead of me.'
Before this week, Sorenstam hadn't played an LPGA Tour event since tying for 31st at the Women's British Open last month.
She is now third on the LPGA Tour's money list with more than $1.57 million, behind the other three-time winners this season, Lorena Ochoa and Karrie Webb.
Kerr birdied three straight holes from the 14th and closed with a five-under 67 to take second place at 17-under 271.
Hjorth had a double-bogey at the 16th, then birdied the 18th to shoot 70 and share third place with Seon-Hwa Lee and Il Mi Chung at 16-under 272. Lee and Chung both closed with 69.
Brittany Lang (66), Nancy Scranton (69) and Kyeong Bae (68) tied for sixth place, one shot further back at 273.