Park, the youngest player to win the 63-year-old championship, closed with a 2-under-par 71 for a total of 9-under 283.
Helen Alfredsson shot a 75 and took second place at 287.
"I am very honored to win this event. I still can't believe I did it," said Inbee Park, who won the U.S. girls junior title six years ago.
"It's just so amazing, I am so honored. It has been 10 years since I started playing golf and it (a pro win) finally happened, so I am excited about that."
The champion's check was $585,000.
The tour's two biggest stars finished far down the list.
Annika Sorenstam eagled the final hole, ended up with a 5-over-par 78 and tied for 24th place, and top-ranked Lorena Ochoa carded a 74 and finished in a tie for 31st place.