'Right now I'm just totally relieved,' said Sorenstam. 'I fought so hard today and over the last three days. You know my game hasn't been on top, but unconsciously I fought through everything.'
Heather Bowie, Pat Hurst and defending champion Se Ri Pak shared second place at 1-under-par 215.
Sorenstam led by two shots entering the round, but bogeyed each of the first two holes to drop into a share of the lead. Bowie, who birdied the first, bogeyed the second to share first with Sorenstam at minus-2.
'I started with two bogeys, obviously not the start I would like, but I hung in there,' said Sorenstam, who earns $225,000 with the victory.
The big swing came at the par-4 fifth. Sorenstam birdied, while Bowie faltered with a bogey to fall two shots back. Sorenstam went on to birdie the sixth and seventh to open a three-stroke lead.
Sorenstam's lead dropped to two shots when Pak birdied the 13th. The lead was briefly one shot when Sorenstam bogeyed No. 13, but Pak dropped a shot moments later at the 15th to fall two back.
The Swede rolled in a lengthy bogey putt on 15, to remain two ahead of Hurst and Pak. The putt may have been the turning point as Sorenstam cruised from there.
'I was struggling with myself more than anything to stay positive,' the Swede said. 'No. 15 is a typical example. It's just horrendous golf, but then I fought and made a long putt for bogey and I saved myself. I am glad I turned it around.'
Hurst and Sorenstam both parred the par-3 16th. Then on the par-5 17th, Sorenstam two-putted for birdie at the par-5 to take a three-shot lead. She capped her 43rd career victory with another birdie at the last.
'This is only April and I'm very, very tired and this is kind of a conclusion,' Sorenstam said. 'I am mentally worn out, and to be able to finish birdie-birdie giving everything I had, that's very satisfying.'
Sorenstam puts another notch in her stellar career. She moves into seventh place on the all-time wins (43) list, five behind Nancy Lopez. This victory was also her 134th top-10 finish in 200 career LPGA starts.
Pak climbed into contention with three birdies and one bogey on the front nine. She moved to minus-3 with a birdie at the par-4 13th. However, the defending champion could not sustain her momentum as she bogeyed the 15th and 16th to complete her round of 1-under 71.
Hurst had several opportunities to make a charge but she could not get going. She posted one birdie and one bogey on the front and back nines for an even-par round of 72. Hurst missed several good birdies opportunities on the back nine.
Bowie tied Sorenstam atop the leaderboard at the first when she rolled in a birdie putt and remained tied with the eventual winner when they both bogeyed the par-4 second. Bowie notched one birdie and one bogey the rest of the nine to make the turn at even-par for her round and three shots off the pace.
Around the turn, Bowie's chances of winning were squashed when she double bogeyed the par-4 14th. Bowie did come back with a birdie at the par-5 17th that helped cap a round of 1-over 73 and her best-ever finish on the LPGA Tour.
Michele Redman finished alone in fifth place at even-par 216. Sophie Gustafson and Jeong Jang were one stroke further back at 1-over-par 217.