Webb finished with a 7-under 65 to reach 11 under on Siam Country Club's Pattaya Old Course. The Australian aced the 159-yard 12th hole with a 6-iron Friday and followed with a bogey and a par before play was called for the day. She also birdied the final four holes on the front nine.
South Koreans Jiyai Shin and Na Yeon Choi were tied for second. Shin completed her 66 on Friday. Choi finished off a 68 on Saturday, matching Webb with a birdie on the par-4 17th.
Norway's Suzann Pettersen (67), Sweden's Caroline Hedwall (65), South Korea's Amy Yang (69) and Japan's Ai Miyazato (70) were 7 under. Pettersen and Hedwall finished Friday. Yang played four holes Saturday, and Miyazato finished the final five.
Top-ranked Yani Tseng, the defending champion, topped the group at 6 under with a 65. The Taiwanese star finished the round Friday.
Michelle Wie followed her opening 75 with a 68 on Friday to reach 1 under.