The 37-year-old closed with an eagle on the par-5 18th to finish the Astara Golf Championship 16 under at the Country Club of Bogota.
American Kevin Dougherty had a 68 and finished alone in second, while Gibson's countryman Brett Drewitt (68) tied for third, a shot further back.
It was Gibson's second win on the secondary tour, and his first since the rain-shortened 2019 BMW Charity Classic in South Carolina. He moved to No.3 on the season points list as he seeks a return to the PGA Tour.
"This is pretty vindicating," Gibson said.
"That (win) was a little truncated. We knew going into the third round it was going to be the final round. To get four rounds done, play awesome on the weekend, bogey-free on Sunday, it just takes the cake. I'm over the moon."
It also marked the largest margin of victory in a Korn Ferry Tour event since David Kocher's six-stroke win at the 2022 Price Cutter Charity Championship last July.
Gibson, from Lismore in the northeast of NSW, left Australia at age 18 and played for Oklahoma Christian University between 2005-08.
"It's pretty surreal to pack my life up in a suitcase and come to America and go to Oklahoma," Gibson said.
"I didn't even know where it was without an atlas back then."
In addition to being the lowest round of the week, Gibson's 64 tied the lowest final round posted in the 13-season history of the event after Chile's Mito Pereira achieved the feat in 2020.
The Korn Ferry Tour now has a month off before beginning its US schedule and Gibson has some big plans for his break.
"I haven't been to Australia since COVID," he said.
"I've seen my parents, but not many other people. Pretty excited to get home."
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