The 14-year-old Park, from Buena Park, Calif., was playing in her first USGA championship.
The score was tied after the first 18 holes on the 6,391-yard Tacoma Country & Golf Club course, but the 17-year-old Kaneko missed a number of putts and hit her ball under a tree on two occasions.
After the 19th hole, Park went in front for good and her lead continued to grow until both golfers conceded bogies on the 33rd hole.
'I was really nervous in front of all those people out there,' Park said after her victory. 'I was too stiff on the first 18 holes.'
Park, who won the AJGA Kathy Whitworth Invitational and was runner-up at the Rolex Tournament of Champions, will represent the West team at this year's AJGA Canon Cup.