Former junior French Open champion Popyrin scored a stunning 4-6 6-0 6-2 triumph in just under 85 minutes.
The 21-year-old from Sydney will see move to No.82 in the world, a career high, when the new rankings are released next week.
"We put in a lot of hard work in pre-season and it's paying off with the start of the year that I had in Australia," Popyrin said in his on-court interview.
"You know I felt really good playing there also so it's just great to see all the hard work paying off.
"Also my family behind the scenes ... they've sacrificed so much for me and to finally win a tournament just shows how much hard work they put in with me also and this is for them, this is for them 100 percent."
Popyrin was broken in the fifth game of Sunday's final and his long forehand gifted Bublik, who was also seeking his first ATP title, the opening set at the second time of asking.
Popyrin won all 12 points on serve in the second set and broke 23-year-old Bublik three times to take it 6-0 in just 20 minutes and level the contest.
The pair had met just once prior on the ATP Challenger Tour in 2018 in Astana when the Australian rallied from a set down to win in three sets, and Popyrin was hoping for a similar outcome.
On serve but down 3-2 in the deciding set, Bublik double-faulted twice to give the Aussie the crucial break.
The Kazakh handed the title to Popyrin minutes later after his serve failed him again, double faulting again and broken for the fifth time in the match to lose it 6-2.