Korda's first US Open win is the fourth major victory of her career, and she claimed it with a steady two-under 69 in the final round.
But it came after she had to watch her second putt for par from inside a metre on the 18th green catch the left edge and tour half the circumference of the hole before dropping.
"It's even sweeter, especially with that ice cream swirl on the last hole," said Korda, who put her hand over her open mouth in disbelief before finally laughing at her last shot.
Korda made a 9-foot birdie putt on the 17th to break out of a four-way tie for the lead with Lopez, the hard-charging Hull and three-time major champion In Gee Chun.
She finished at eight-under 269 after sharing the lead with multiple competitors throughout the windy finale of the first Women's Open ever held at 100-year-old Riviera in Los Angeles.
"I didn't feel my best on the back nine," Korda said. "I had a lot of emotions swirling in my stomach, (but) it's a dream come true. I've dreamt about this moment since I was a little girl."
The 27-year-old Korda has stressed positivity and steadiness after her inexplicably winless 2025, and it has paid off with one of the most outstanding starts to a season in recent golf history.
She won opening major, the Chevron Championship in April, and had three victories and three second-place finishes in her first seven starts of the year.
After a rough opening-round 73 at Riviera, she put together back-to-back 67s to take a share of the lead into the final round.
"This week was definitely a grind," Korda said. "I don't even feel like I had my B game. I was just grinding out there, and that's what I guess major championships are all about, right? It doesn't matter if you have your B or C game. You have to be there mentally."
Starting the day three shots back, England's Hull charged and led before finishing with a 67 to tie for second with Mexico's Lopez who posted a 68.
Chun (70 was outright fourth at six under, a shot ahead of fellow South Korean Sei Young Kim (72).
Youngsters Grace Kim (69) and Karis Davidson (73) tied for 22nd, 10 shots behind Korda and a shot ahead of fellow Australians Hannah Green (69) and Minjee Lee (71).
