Saso entered the final round five strokes off the pace. Ireland's Leona Maguire was the overnight leader on Saturday at 7-under 206 at Baltusrol Golf Club in Springfield, New Jersey.
On Sunday, Saso had her best round of the tournament, shooting a 5-under 66, including five birdies on the first 15 holes, to move into title contention. The round was interrupted by a rain delay that lasted about two hours.
Saso, who was born in the Philippines to a Japanese father and Filipino mother, was tied for the lead with three holes remaining.
On the par-4 16th, Saso had her lone bogey of the round, and followed with an even-par effort on the next hole.
Saso, who turned 22 on June 20, wrapped up the tournament with a birdie on 18, reaching the green from the bunker. That gave her a 7-under 277, including rounds of 69, 73 and 69 entering the final day.
Yin, who had no bogeys in the final round, secured the win with a birdie on the final hole, taking the title with an 8-under 276. The 20-year-old is the second Chinese woman to win a major, following Shanshan Feng, who captured the top prize when this event was known as the LPGA Championship in 2012.
Inspiration for Yin
Reflecting on Feng's influence on her career, Yin said, according to The Associated Press that "I think she is the person who inspired me the most."
Reliving the drama of the 18th hole, Yin said she felt pressure to deliver a clutch performance to end the round.
"After the tee shot, I saw Yuka make an incredible birdie here," Yin was quoted as saying by Agence France-Presse. "I knew I had to make birdie at this hole to win the championship and I'm glad I did it."
Saso Analyzes Her Golf Game
Saso, who became the second teenager to win a women's major at the 2021 US Women's Open, said she closed out Sunday's round with a solid effort on the 18th hole.
"After missing the birdie on 17, I just wished that I wouldn’t hit my drive in the water on 18," Saso told reporters. "But glad I didn’t. [I] hit a good shot, and the second shot hit it in the left bunker. It was not an easy bunker shot, but it was manageable, and I was able to manage it pretty good."
Saso tied for seventh in her previous tournament, the Mizuho Americas Open (June 1-4) in Jersey City, New Jersey.
Before that, she missed the cut in four straight tournaments.
It's been a learning experience, according to Saso, referring to her 2023 season.
"Just keep doing what I've been doing, I guess, and trusting myself, trust the process," Saso told reporters after her runner-up finish. "Nothing comes easy, and … I think I will still struggle for the season. I don't know, I hope not. But I'm pretty sure I will, [and] I think I'm ready to face it."
A quintet of golfers tied for third, two shots back at 278.
American Rose Zhang, the first LPGA golfer to win her debut tournament (Mizuho Americas Open) since 1951, when Beverly Hanson triumphed at the Eastern Open, South Korea's Jenny Shin and Japan's Ayaka Furue finished tied for eighth at 5-under 279.
Also in the final round, Maguire had a 3-over 74. She tied for 11th at 280.