The 20-year-old Thai star fired a four-under par 67 in the final round to finish 72 holes on 20-under 264 at Highland Meadows in Sylvania, Ohio.
Ryu birdied four of the last five holes and six on the back nine but her lone bogey at 16 dropped her one adrift of Chanettee before both contenders birdied the par-5 17th and 18th holes to give Chanettee the triumph.
“Actually today I’m really nervous, and get stressed,” Chanettee said.
“This year I didn’t expect I was going to win, so lots of stress and nervousness.
“On the last putt on the last hole my hand is shaking so hard. I’m just like, ‘Get in, get in. I want birdie, not par.’ I made it.”
Sweden’s Linn Grant, the 2023 Dana Open winner, and Taiwan’s Cheng Ssu-Chia each fired a 68 to share third on 270 with China’s Mary Liu and Lin Xiyu sharing fifth on 272.
Chanettee, ranked 43rd, won her only prior LPGA title at last September’s Portland Classic as a Monday qualifier.
“I’m starting this year looking for second trophy so right now I can’t imagine,” Chanettee said. “Portland, I feel like freedom. Right now I’m feeling like I’m going to looking for third trophy. I think it’s coming.”
This year, she was third at the Americas Open in May and shared eighth at last month’s Dow Championship before breaking through for a second LPGA victory.
“This week is like a lot of experience,” Chanettee said. “I think I’m going to improve my skill.
“Last day I cannot like calm down because my heart is like boom, boom, boom, boom. Every hole. I think I’m going to improve my emotion and my skill.”
Ryu, last year’s LPGA Rookie of the Year, won her only LPGA title at last October’s Northwest Arkansas Championship. She has seven top-10 showings this season.
“Really good shots and almost get it,” Ryu said. “I think that’s highlight this week.
“I think now my (finishing) first really good and hopefully move up for next tournament.”
Chanettee, who began the day with a three-stroke lead, surged early with birdies at the third, par-5 seventh and par-3 eighth while Ryu’s only front-nine birdie came at the par-3 sixth.
Ryu charged on the back nine with birdies at 10 and 12 and added birdies at the par-3 14th and 15th.
Chanettee, meanwhile, stumbled with a bogey to begin the back nine and a birdie-bogey run at 12 and 13.
Deadlocked for the lead, Ryu made her first bogey at 16 to fall one stroke back and Chanettee and Ryu both birdied the last two holes to deliver Chanettee the trophy.
Sharing seventh on 274 were Filipino Dottie Ardina, Thailand’s Jasmine Suwannapura, Norway’s Celine Borge, Australian Sarah Kemp, American Stacy Lewis and South Korean Choi Hye-jin.
South Korea’s Joo Soo-bin made a hole-in-one at the par-3 second hole, sinking the 151-yard ace with a 6-iron.
Schauffele wins British Open
Elsewhere, Xander Schauffele said a “sense of calm” helped him win the British Open yesterday as the American claimed his second major just two months after triumphing at the PGA Championship.
The 30-year-old Californian delivered a faultless, zen-like six-under-par final round at Royal Troon to emerge from a congested leaderboard and clinch the Claret Jug.
Schauffele finished on nine-under par for the championship, two shots ahead of England’s Justin Rose and Billy Horschel of the USA.
Schauffele, who registered a major record of 21-under-par to win the PGA at Valhalla in May, is the first player to win two majors in a year since Brooks Koepka in 2018.
His victory on the west coast of Scotland completes an American clean sweep of the game’s biggest titles in 2024.
“I thought (winning the PGA) would help me and it actually did. I had this sense of calm, a calm I didn’t have when I played earlier at the PGA,” said Schauffele.
“I was telling my caddie Austin (Kaiser) that I felt pretty calm coming down the stretch and he said he was about to puke on the 18th tee.”
“I just told myself to just hit it down there and keep moving along,” added the world number three, who described clinching the Open as a “dream come true”.
Schauffele had started the last 18 tied for second with five other players, a shot behind overnight leader Horschel.
He put together a tidy front nine under benign conditions on the links course, reaching the turn at two-under par for the day after birdies at the sixth and seventh.
He then burst into life at the start of the inward half as his nearest challengers - former US Open champion Rose, world number 62 Horschel and South African Thriston Lawrence - began to falter.
Schauffele hit a sublime approach to the difficult 11th to set up a tap-in birdie before sinking a 16-foot birdie putt on the 13th to get to seven under alongside 27-year-old Lawrence.
Moments later Schauffele was in front on his own after Lawrence dropped his first shot of the day on the 12th.
The American then rolled in a 12-footer on hole 14 and suddenly he had a two-shot lead. That extended to three after a delightful chip over a bunker at the 16th led to another birdie.
Two closing pars sealed the championship.
Lawrence, bidding to join a high-profile list of South Africans to have lifted the Claret Jug including Gary Player, Ernie Els and Bobby Locke, had held a one-shot lead at the turn.
Mentality
Rose, US Open champion in 2013, briefly enjoyed a share of the lead with Lawrence after hitting three birdies in his opening nine holes.
But he bogeyed twelve before too-little-too-late birdies on 16 and 18 put him on seven-under.
England’s Rose, ranked 67th, said that Schauffele’s strong mentality was under-appreciated.
“He’s such a calm guy out there. I don’t know what he’s feeling, but he certainly makes it look very easy. He plays with a freedom, which kind of tells you as a competitor that he’s probably not feeling a ton of the bad stuff.”
America’s Horschel suffered an inconsistent opening ten holes before birdieing the last three to finish tied for second with Rose.
Lawrence finished on his own in fourth at six under, while American Russell Henley was a shot further back in fifth.
Ireland’s Shane Lowry, the leader after two rounds, posted a 68 to finish four-under par and in sixth place.
World number one Scottie Scheffler and two-time major champion Jon Rahm both briefly threatened a run up the leaderboard but finished tied for seventh on one under alongside South Korea’s Im Sung-jae.
Several stars struggled this week due to the testing weather conditions, thick rough and well-placed punitive pot bunkers.
Rory McIlroy missed the cut, extending his decade-long wait for a fifth major into 2025, as did US Open champion Bryson DeChambeau, Ludvig Aberg, Wyndham Clark and Viktor Hovland.
Three-time champion Tiger Woods also missed the weekend, recording his worst-ever performance at the Open with a 14-over score of 156.
Home favourite Robert MacIntyre finished nine over after failing to repeat the heroics that secured last week’s Scottish Open.