The 22-year-old Nordqvist, a native of Sweden, finished at 13-under 203 for her second win on the tour. In June, she won the 2009 McDonald's LPGA Championship, one of the four women's majors.
"It was great. To win two times, I'm just so happy," Nordqvist said.
Nordqvist, who won $225,000, was 11-under for the last two rounds at the Houstonian Golf & Country Club.
Ochoa, the top-ranked woman golfer, closed with a 67 and 205.
The Mexican star's finish was good enough to give her the tour's Player of the Year award for the fourth straight year.
Na Yeon Choi (64) and Kristy McPherson (70) tied for third place at 206.
The tournament, which ended the LPGA season, was shortened to three rounds because rain forced cancellation of play Saturday.