Tied for the lead with Kupcho after each of the first two rounds and a stroke ahead entering the day at the Golden Ocala Golf Club, Ernst closed with a two-under 70 to finish at 15-under 273.

Kupcho, coming off a closing eagle on Saturday, had a double bogey and three bogeys in a 74.

Following sisters Jessica and Nelly Korda in the first two events of the year, Ernst gave the United States three straight victories to open a season for the first time since 2007.

The win for the 29-year-old adds to her successes at the 2014 Portland Classic and the 2020 NW Arkansas Championship.

With brother Drew as her caddie, Ernst birdied Nos. 4-7 to get to 17 under, but dropped back with bogeys on Nos. 12 and 13.

Kupcho birdied 10 and 12 to pull within three strokes of Ernst, then bogeyed 14, made the double bogey on the par-3 15th and bogeyed 17.

She played most of the back nine in the opening round Thursday with a migraine that blurred her vision.

Jenny Coleman made it a 1-2-3 US finish, closing with a 71 to get to eight under.

In Gee Chun of South Korea was fourth at seven under after a 69.

Switzerland's Albane Valenzuela was another stroke back after a 73.

Jessica Korda shot a 71 to tie for eighth at four under while Nelly Korda, tied with Ernst and Kupcho for the first-round lead, had weekend rounds of 76 and 75 to tie for 28th at even par.

Sarah Kemp (71) finished best of the Australians at one over for a share of 34th as Katherine Kirk plummeted 30 spots on Sunday to be tied-48th after a five-over 77.