ST. PETERSBURG -- The feeling sunk in fairly quickly for Theo Gillen. It just didn’t necessarily feel real.

But it is now. Only a few months out of high school, he is now a professional baseball player.

Less than two weeks ago, the Rays made Gillen a first-round pick in the MLB Draft, selecting him 18th overall out of Westlake High School in Austin, Texas. He officially joined the organization on Friday afternoon, reporting to Tropicana Field to sign his contract and begin his career.

“It sinks in like this,” Gillen said, snapping his fingers as he stood in front of the Rays’ dugout. “Then you’re like, ‘All right, what’s next?’ I’m ready to get down there. I’m ready to go compete with my guys. It’s a surreal feeling and it goes by quick. It’s really special.”

Gillen received a signing bonus of $4,372,900, according to MLB.com’s Jim Callis, the full-slot value of the 18th pick. He brought his family, girlfriend, hitting coach and advisor with him to the Trop, where he met many Rays officials, coaches and players.

The 18-year-old Gillen hopes to be here one day, preparing for Major League games. But he was just taking it all in on Friday.

“We’re all kind of starstruck right now, getting to be at the stadium, be around all the big leaguers,” he said. “It’s something special, and I can’t wait for everything else.

“The fact that I’m here and part of the Rays organization, it still doesn’t feel real, really. It’s an incredible feeling and I’m super excited.”

Gillen will report to the Rays’ complex in Port Charlotte, Fla., to get acclimated and get going. Amateur scouting director Chuck Ricci said he was most excited to see how Gillen, a high school shortstop drafted as an outfielder, will handle the transition defensively.

“I think we're just going to put him out there, let him be an athlete,” Ricci said. “We really trust the bat and we think the power is coming and he's strong, and it's not just the tools. I think his plate discipline is really going to translate.”

Originally committed to the University of Texas, Gillen was considered the best pure high school hitter in this year’s Draft class. He hit .415 with four doubles, six triples, seven homers, 30 RBIs, 38 runs and 29 stolen bases as a senior this spring.

Gillen had shoulder surgery to repair a torn labrum as a sophomore in high school, which affected his throwing arm. But he has plus raw power and above-average speed, and the latter should serve him well as he moves to center field.

“I’m going to come in every day, want to get better, want to compete with my guys and win a World Series,” Gillen said. “That’s what I’m here for. I’ve dreamt of it since I was a little kid, and that’s what I want to accomplish.”

The Rays were also blown away by Gillen's maturity every time they met with him, which Ricci said was a credit to his parents, and felt it was another sign he’s ready for the challenge of joining the professional ranks.

“We're ecstatic. I think the more we got to know him, not just on the field but off the field, his family -- I think it just all aligns with everything we value in a player,” Ricci said.

Gillen was one of the Rays’ 21 selections in the 2024 Draft and the 19th to sign in advance of the Aug. 1 deadline. Their top unsigned selection is Illinois high school shortstop Tyler Bell, who went 66th overall in Competitive Balance Round B; he is not expected to sign with the Rays.

The following picks have signed: OF Theo Gillen (Round 1), 2B Émilien Pitre (Round 2), C Nathan Flewelling (Round 3), RHP Nate Knowles (Round 4), RHP Jacob Kmatz (Round 5), RHP Janzen Keisel (Round 6), RHP Ryan Andrade (Round 7), RHP Jayden Voelker (Round 8), LHP Garrett Gainey (Round 9), RHP Trey Pooser (Round 10), RHP Cade Citelli (Round 11), SS Jack Lines (Round 12), OF Connor Hujsak (Round 13), RHP Ryan Schiefer (Round 14), OF Derek Datil (Round 15), 1B Brady Marget (Round 16), RHP Andres Galan (Round 17), LHP Dominic Niman (Round 18) and 3B Tony Santa Maria (Round 19).

“You finally get to this point, and it's really neat to see it all come to fruition,” Ricci said.