In the final round, Kerr shot 3-under 68 to finish at 14-under 199.
Sorenstam, who won this tournament the past two years and began the day trailing Kerr by one stroke, shot a closing 2-under 69. She was 12-under 201 when the event ended.
The win was Kerr's third this season and the ninth of her career.
She sizzled with a career-best round of 10-under 61 Saturday, and her final score tied Sorenstam's tournament record.
"She's played in a lot of tournaments that I've won but not in the same group, so this is probably the first or second time going head to head that I've beaten her," Kerr said. "This is one of the only times I've gotten her."
Kerr won $150,000.