Ko's tally of ten-under is the lowest score ever recorded at the Women's Australian Open, trumping Karrie Webb's nine-under 64 in Melbourne 13 years ago.
Australia's Karrie Webb reduced the gap to three strokes during the third round, played early on Sunday, but she was unable to prevent Shin clinching a second British Open triumph following her win in 2008.
Tiger Woods' niece Cheyenne, who qualified for the tournament soon after turning professional, was tied for 55th on 75 in a group including Australia's former world No. 1 Karrie Webb -- a two-time winner of the tournament.