The Rays' first-rounder allowed four hits over five innings Wednesday in the Class A Short-Season Hudson Valley Renegades' 2-0 win over the Vermont Lake Monsters.
Guerrieri (1-2) threw 56 pitches, struck out four batters and did not issue a walk.
"It's an honor to be named an All-Star," said MLB.com's No. 82 prospect. "It's definitely a great achievement and I'm stoked.
"It feels great to get [my first win]. It took long enough, but I finally got there. I think I've pitched well enough for a couple more wins, but baseball is a crazy game and you can't expect too much."
Guerrieri gave up hits in four of his five innings, but he didn't allow more than one baserunner in any one frame. Only one Vermont batter advanced past second base.
Brett Vertigan singled off third baseman Richie Shaffer's glove in the first inning, but he was stranded at second base. Jacob Tanis then stroked a clean line drive to right field with two outs in the second, but he did not make it past first.
After pitching a 1-2-3 third, Guerrieri worked around John Wooten's one-out double in the fourth. Sam Roberts singled back up the middle in the fifth frame, but the Rays' No. 4 prospect induced consecutive ground balls to wrap up his outing.
"I was getting ahead of the batters, and my changeup and curveball were working. I was throwing my fastball 80 percent, 90 percent of the time and that was the key to my success. That is my go-to pitch, it's the pitch I have the most command with.
"The hits were definitely mistakes. I missed my spots, props to them."
Ian Kendall allowed one hits and three walks while striking out two batters over three innings of relief, and Shay Crawford fanned one batter in a perfect ninth to earn his third save of the year.
Guerrieri felt good enough to come back out for another inning, but accepts that the organization has him on a strict pitch count in his rookie year.
"I was up to 56 pitches, but I will be five innings for the remainder of the year -- five innings or 75 pitches, whichever comes first," said Guerrieri, who posted a 1.10 ERA as a pitcher in high school while batting .507 with nine homers at the plate. "I definitely could have gone six or seven innings tonight with my pitch count, but I understand what the Rays are doing and I respect that. Sometimes you would like to go deep, but I'm fine with that."
With the win, Guerrieri -- selected 24th overall in June's Draft -- lowered his ERA to 1.06. It would rank third in the league if he had pitched enough innings to qualify.
He made his debut June 20, and he has been sharp ever since. He has allowed two runs just once in eight starts, and on four occasions, he has put up zeros. The right-hander has 29 strikeouts over 34 innings, and he has walked just two batters, none in his last four outings.