Schauffele shot a seven-under 64 on Sunday to win the Baycurrent Classic in Japan - a country where his mother grew up and where he has many connections.
The American, who shot 19-under 265 over four rounds at the Yokohama Country Club, finished one shot ahead of American Max Greyserman, who was also the runner-up at this event a year ago as he chases his first PGA Tour title.
Australian Min Woo Lee capped off a solid tournament by claiming a share of 10th place after rounds of 73, 65, 67 and 68 (273) to finish eight shots behind Schauffele.
It was Lee's first top-10 finish on the PGA Tour since winning his maiden title in the US at the Houston Open in March.
Schauffele has maternal grandparents living in Japan and his mother has roots in Taiwan and grew up in Japan.
His mother-in-law is also Japanese, and his wife is half Japanese and grew up in the southern island of Okinawa.
"I've been coming here since I was about nine years old to visit my grandparents," Schauffele said.
"I sort of fell in love with this country a long time ago. I can't wait to bring my son here when he's old enough to sort of understand and appreciate the culture here in Japan.
"Yeah, the ties run deep for the Schauffele family here in Japan.''
Schauffele and his wife Maya became parents just over a month ago with the birth of a son.
"It's still kind of fresh, but it's definitely a cool thing being a dad, and I'm so excited to go home to him and Maya after this," Schauffele said.
Schauffele was cheered during the tournament by family members who attended, including his 81-year-old grandmother, who walked the course with him. He said there would probably be a get-together with family members later to celebrate.
"I mean, I don't get to see them very often and they've always been gracious with their time to come out wherever the event was," he said.
"They've been awesome to me and this is pretty cool. I've really wanted to share a win with them, so can't wait to get together with them."
Greyserman closed with a 65 and held or shared the lead through the first three rounds. American Michael Thorbjornsen finished with a 64 and was three strokes behind the winner.
Schauffele has won two major championships - including the British Open in 2024, which was his most recent victory - and took gold in the Tokyo Olympics, which were delayed until 2021 by the pandemic.
He has also compiled a considerable list of other PGA Tour titles, but this title is different
.Soft conditions and gentle winds led to low scoring on Sunday. American Matt McCarty shot an 11-under 60, yet he still finished nine strokes back.
McCarty had a chance at a 58, but hit into the trees on his final hole and had to settle for a bogey and a 60.
Jim Furyk holds the PGA Tour record with a 58 in the final round of the 2016 Travelers Championship.
Japan's Takumi Kanaya closed with a nine-under 62 and finished five shots behind the winner.
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