PHOENIX, March 24, 2014 (AFP) - The 39-year-old Australian closed with a nine-under 63 to finish with a 19-under 269 and win this event for the second time in three years.
"I stood on 10 tee and thought 20-under would have a chance. I thought at 19-under I'd definitely be in a playoff, if anything, not standing here as a winner," Webb stated.
"I wasn't nervous, it was out of my control really. My job was done, and I just had to wait and see."
This was Webb's second win of the year, and 41st of her career on the LPGA Tour.
Last year's winner Stacy Lewis earned a share of second at 18-under by shooting a six-under 66 at the Wildlife Golf Club.
Lewis tied with Amy Yang (67), Azahara Munoz (67), Mirim Lee (69) and New Zealand's Lydia Ko (70).
Lee led after the first two rounds, while Ko was atop the leaderboard entering the final round.
Thailand's Pornanong Phatlum (66), Jessica Korda (70) and Ryu So-Yeon (68) tied for seventh place at 17-under 271.
Webb started the day six strokes behind Ko, and she played 10 groups ahead of the leader.
Webb made a birdie on the ninth hole to make the turn at 13-under, where she was still six shots behind.
Ko, 16, faltered to bogeys on the ninth and 11th to slip into a share of the lead at 18-under. Meanwhile Webb was red hot around the turn.
After a par on 17, Webb made a 20-footer for birdie at the last to end at 19-under.
Ko was finishing the 10th hole as Webb headed to the club house, then to the range in case someone caught her and forced a playoff.
Munoz, Yang and Lee all had birdie attempts on the 18th hole to try and get into a playoff, but none were successful.
"I had a really good start," Ko said. "Making four birdies on the first five holes was really good, and I struggled in the holes after that, but you know, I tried to get myself together, and I made some bogeys in the wrong time, which wasn't ideal, but I tried my best until the last."
Leading scores on Sunday after the fourth round of the LPGA Founders Cup (par 72, USA unless noted):
269 - Karrie Webb (AUS) 66-71-69-63
270 - Stacy Lewis 66-71-67-66, Amy Yang (KOR) 67-69-67-67, Azahara Munoz (ESP) 68-71-64-67, Mirim Lee (KOR) 64-67-70-69, Lydia Ko (NZL) 67-66-67-70
271 - Pornanong Phatlum (THA) 67-71-67-66, Jessica Korda 69-66-66-70, So Yeon Ryu (KOR) 68-67-68-68
272 - Cristie Kerr 73-69-63-67, Inbee Park (KOR) 66-69-70-67
273 - Michelle Wie 66-70-67-70, Lizette Salas 69-67-69-68, Caroline Masson (GER) 70-71-66-66