Pettersen collected her second LPGA major tournament title by winning the rain-shortened Evian Championship in France, finishing two strokes ahead of Ko. It was Pettersen's third LPGA win this year and fifth in the last 12 months.
Her other major tournament victory came in the 2007 LPGA Championship.
Pettersen moves past Stacy Lewis, who tied for sixth at the Evian, for second in the rankings.
Ko, a 16-year-old from New Zealand, takes over the No. 5 spot in the ranking, moving up from eighth. Her ranking point average is just 0.04 behind No. 4-ranked Choi Na-yeon.
Only No. 1-ranked Inbee Park and Choi hold the same spots in the Top 10 as they did a week ago. Most of the changes were one place in the rankings but Catriona Matthew slips three places to 10th. However, Matthew's average is only 0.l52 points behind that of No. 7 Karrie Webb.
The LPGA is off for two weeks when it begins a series of Asian tournaments.
The world women's golf rankings Top 10, listing player's name, home country, rankings points average and finish at the Evian Championship:
1. Inbee Park, South Korea, 12.53, tie for 67th
2. Suzann Pettersen, Norway, 10.72, first
3. Stacy Lewis, United States, 9.85, tied for sixth
4. Choi Na-yeon, South Korea, 7.45, tied for 44th
5. Lydia Ko, New Zealand, 7.41, second
6. Ryu So-yeon, South Korea, 7.33, tied for fourth
7. Karrie Webb, Australia, 6.11, tied for 15th
8. Feng Shanshan, China, 5.67, tied for 11th
9. I.K. Kim, South Korea, 5.64, tied for 19th
10. Catriona Matthew Scotland, 5.59, tied for 64th