Australian Minjee Lee secured the biggest prize in women's golf with an emphatic four-stroke victory at the U.S. Women's Open at Pine Needles on Sunday.

Lee shot 71 and finished at 13-under-par 271, collecting $1.8 million from a record total purse of $10 million, while American Mina Harigae (72) claimed second place on nine-under.

"It's such a great honour. It's been my dream since I was a little girl. It's the one I've always wanted to win so now I've done it and it just feels amazing," said the 26-year-old from Perth.

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"It's such a large sum," she added, almost lost for words as she tried to articulate what it meant to win nearly $2 million in one hit, not quite sure what she would do with the money.

Lee, who won her first major title at last year's Evian Championship, joins Karrie Webb (2000 and 2001) and Jan Stephenson (1983) as Australians to win the U.S. Women's Open.

Starting the final round with a three-shot lead over Harigae, Lee quickly extended her advantage.

A two-putt birdie at the par-five first was followed by a 40-foot bomb at the second that was greeted initially with complete silence because the hole on the elevated green was not visible to the gallery.

Though she had a couple of bogeys on the demanding front nine, nobody could make a run as a fluctuating breeze, firm conditions and tucked hole locations turned the round into a battle of attrition.

Using her deceptively powerful swing to regularly outdrive Harigae by 30 yards or so, the diminutive Lee also putted with authority and was far enough ahead to almost enjoy the final few holes.

"I was pretty nervous all day," she said. "It was nice to have that little buffer."

The daughter of Korean parents who emigrated to Australia, Lee swam competitively from an early age before turning her attention to golf around the age of 10, taking her work ethic from one sport to the other.

"I think this will be huge for all the little girls and even the boys and the children watching (in Australia)," she said.

"Hopefully they watch me on TV and I can be a good role model to them and they'll start getting more involved."