The 18-year-old New Zealander shot a final round three-under 69 to finish 12-under-par, ensuring her second successive major title having won the Evian Championship last year.

England’s Charley Hull and South Korea’s Chun In-gee, the reigning US Open champion, both ended up a stroke back.

"It was always my dream to play on the LPGA," Ko, who came into the event on the back of a three-shot win at last week’s Kia Classic, said.

"Just being here was a dream come true.

"For these amazing things to be happening is unbelievable, but it also motivates me to work harder."

Thailand’s Ariya Jutanugarn had a two-stroke lead over Ko with three holes remaining but a disastrous trio of bogeys saw her finish two shots off the pace.

Ko secured her 12th LPGA Tour victory by firstly getting up-and-down for par at the 17th and then playing a precise wedge into the par-five 18th to set up what proved to be a decisive birdie putt.

She had begun the day tied for second, one shot behind the leader Lexi Thompson of the United States, who was hoping to claim her second ANA Inspiration title in the last three years.

Bogeys on two of the first three holes de-railed Thompson's challenge, but she eagled the final hole for the second time in as many days to finish three shots behind Ko in fifth place.

Defending champion Brittany Lincicome, also from America, finished 10 shots off the pace after a final round 74.

Joint runner-up Hull was full of praise for the manner of Ko's triumph.

"Lydia hit a great shot into the last and she should be proud of herself," said the 20-year-old. 

"I think [my performance] was great. 

"I can't wait for the next tournament.

"I put some good work in over Christmas and so far I have had a number of top-10s and been playing well."