The 24-year-old Piller finished at 12-under 272 on the University of Georgia Golf Course and earned $99,000 to jump from 16th to second on the money list with $157,886.
Summerhays took a share of the lead to the final hole, but finished with a bogey after pushing his 6-iron approach. He settled for a 73.
Piller two-putted for the victory after hitting an 8-iron to 8 feet.
“I was shaking. I couldn’t believe how nervous I was,” Piller said. “It was the first time in my life that I really thought about how hard it was to two-putt. Luckily, the putt was straight uphill. I couldn’t have had an easier putt.”
Piller is $28,497 behind former college roommate Bobby Gates on the money list. Gates finished with a 73 to tie for seventh at 5 under.
“He came up to me after and congratulated me and said, ‘Good win, but you’re still behind me,”’ Piller said. “It gives me motivation. We’re good friends and we hate losing to each other. It’s just a testament to Texas A&M and the players they’re producing.”
Gary Christian (66) was third at 10 under.