AUBURN, 20 Jul 2015 (AFP) - The 36-year-old American finished the week at 19-under 265 to breeze to a three-stroke victory over runner-up Will Wilcox, who had a 67.
"I struck it awesome. I am really excited," Piercy said.
Piercy, who missed five months last season after undergoing elbow surgery, had won previously at the 2011 Reno-Tahoe Open and the 2012 Canadian Open which begins next Thursday.
Amateur Robby Shelton tied for fourth with Ricky Barnes and South Korea's Kim Whee at 270. Shelton shot a 67, Kim posted a 69 and Barnes, who was the co-leader after the third round with Piercy, shot a 70.
Andrew Loupe (65), Boo Weekley (67), Austin Cooke (67) and Australia's Mark Hensby (70) shared sixth place at 271. Six players tied for 10th at 272.
There were 15 players within four shots of the leaders heading into the final round but for the first time in the last four US Tour tournaments there was no playoff to determine the winner Sunday.
Piercy is ranked 42nd in the FedEx Cup playoffs heading into the Barbasol. His best previous finish this season was a second at the Sony Open in Hawaii. He also has two top 10 finishes at the Shriners Hospitals Open and the Houston Open.
Piercy wasted no time distancing himself from playing partner Barnes as he drained birdies on his first two holes en route to five birdies on the front nine.
He sank three birdies in a four hole stretch on the back beginning at the par-five 13th.
The Las Vegas native really showed his swagger on the par-fives Sunday as he birdied all three.
Piercy said he enjoyed one of his best hitting days since he turned pro in 2001.
"I hit 17 greens and almost all the par-fives in two shots. It is pretty hard to lose when you do that," he said.
Wilcox was unable to catch Piercy despite sinking birdies on numbers 17 and 18. He capped his round in dramatic style by pouring in a 58-foot putt on the 72nd hole.
That touched off a fist-pumping celebration as his four-under 67 allowed him to retain his US Tour card for next season.
"The fact I kept my card in 13 starts is awesome," said the 29-year-old American. "That is something I can hang my hat on."
Leading scores after Sunday's final round of the USPGA Tour's Barbasol Championship (USA unless noted, par-71, a-denotes amateur):
265 - Scott Piercy 69-66-65-65
268 - Will Wilcox 66-70-65-67
270 - Ricky Barnes 67-68-65-70, Kim Whee (KOR) 67-66-68-69, a-Robby Shelton 68-69-66-67
271 - Boo Weekley 67-69-68-67, Mark Hensby (AUS) 69-64-68-70, Andrew Loupe 68-70-68-65, Austin Cook 69-70-65-67
272 - Aaron Baddeley (AUS) 69-72-64-67, Johnson Wagner 69-68-66-69, Andres Romero (ARG) 71-64-69-68, Vaughn Taylor 71-69-63-69, Emiliano Grillo (ARG) 68-66-67-71, Blayne Barber 69-67-68-68
273 - Jason Gore 65-73-63-72, Scott Langley 72-67-69-65, Tom Hoge 68-71-69-65
274 - David Toms 69-66-72-67, Jonathan Byrd 68-69-69-68, Martin Flores 66-74-68-66, Martin Piller 69-66-70-69