The New Zealander started the final round in a share of fourth but made three birdies over a flawless first 14 holes to challenge for the title, which boiled down to a thrilling finale between Ko, Nelly Korda and Lilia Vu tied at the top of the leaderboard on six under par.

Ko took the clubhouse lead with a brilliant birdie on the 18th, but defending champion Vu was still on her heels right to the end.

Vu needed a birdie to force a play-off, but ran up a bogey five to secure victory for Ko.

A third major title caps off a fantastic couple of weeks for Ko after she took Olympic gold earlier this month.

Speaking at the trophy presentation, Ko – who had recorded 11 top-10 finishes at majors since her last win at the Chevron Championship eight years ago -said: “It’s pretty surreal. Winning the gold medal in Paris a couple of weeks ago, it was almost too good to be true.

“Obviously heading into the weekend I was in contention, I said ‘how is it possible for me to win the AIG Women’s Open?’ I’ve had the most Cinderella-like story this past few weeks and this is almost too good to be true.

“To be holding this trophy right now, I can’t believe it and it’s obviously very special this year with my family being here this week too.”

This year’s event saw golfers competing in some strong winds, but Ko insisted she enjoyed her experience over the Old Course despite some difficult weather conditions.

“I think I just had a lot of fun and it was almost so windy that I hit some shots and all I could do was laugh because I’ve never seen a ball react that way,” she added.

“It was difficult but going into the week I think all of us players knew it was going to be tough out there, that’s why it’s a huge round of applause to the team here, the superintendents for making the course playable because it was so windy that it could’ve easily not been that case.

“I’m winded out, but I’ve actually got a golf trip next weekend and it’s meant to be windy there too so at least I’m ready for next week too!”

Vu’s dropped shot at the last saw her finish on five under and in a tie for second with Jiyai Shin, Ruoning Yin and Korda.

Victory slipped away for world number one Korda after she hit the ball into the Road Hole bunker on the 17th, which she subsequently bogeyed.

England’s Charley Hull endured a frustrating final day and eventually finished tied for 20th on one over par.

England’s Lottie Woad won the Smyth Salver, awarded to the leading amateur after a closing birdie gave her a one-under-par total.