"I think I still need to be pinched," Martin told the tournament's official website.
England's Charley Hull, who many in the Northern Hemisphere liken to Ko given the 18-year-old's prodigious talents at a young age, was in contention heading in to the final round but also fell away as she shot a six-over 78 to finish in a tie for 12th at six-over.
"I played rubbish today, to be honest," Hull told reporters. "I was a bit nervous because the ball was moving and stuff on the greens. But I've learned a lot from this round today, again. It's just a shame I couldn't birdie the last to finish inside the top-10."
World No 1 Stacy Lewis finished alongside Hull in a share of 12th place, while third-round leader Inbee Park slipped to fourth at one-over after a final round of 77.
Ko, the world No 2, banked USD$22,977 for her efforts as she continued a strong rookie campaign on the LPGA Tour and also maintained her record of having never missed a cut in a professional tournament.
The next women's major is the LPGA Championship that takes place at the Monroe Golf Club in New York from August 14-17.