Pettersen shot a 3-under 68 to finish with a 10-under total of 203 after the tournament was reduced to three rounds when Thursday's play was rained out. The 16-year-old Ko, who was trying to become the youngest major champion, finished with a 70.
American Lexi Thompson shot a 68 to finish four shots back in third place, with South Koreans So Yeon Ryu and Se Ri Pak five shots behind in a tie for fourth.
Top-ranked Inbee Park aimed to become the first golfer to win four majors in a year but finished way out of contention. This was the first year that Evian counted as the fifth major of the year on the women's calendar.
Jim Furyk was forced to wait one more day to try to end three years without a victory on the PGA Tour. The final round of the BMW Championship was suspended Sunday in Lake Forest, Ill., because of rain that left too much water on Conway Farms. Furyk had a one-shot lead over Steve Stricker. Furyk was among 22 players who did not tee off Sunday. Only six players completed their rounds. Rory McIlroy had a 68 and was able to get an early start on his four-week break.
Suzann Pettersen -10
Lydia Ko -8
Lexi Thompson -6
So Yeon Ryu -5
Se Ri Pak -5