Carlson took batting practice on the field prior to the game with the Astros.
"It's a surreal moment I'll never forget," Carlson said of putting on the Cardinals uniform for the first time. "It's something I'll always cherish. I just appreciate this opportunity and can't thank the Cardinals enough. I'm ready to go play."
Cardinals hitting coach John Mabry threw batting practice to Carlson, who showcased his switch-hitting prowess in the cage.
"I feel comfortable on both sides," said Carlson, who also met manager Mike Matheny. "I've been switch-hitting since I was 5 years old. They both feel natural. I feel I'm a strong hitter from both sides and have plenty of room to improve."
Carlson did not rank on MLB.com's list of Top 200 Draft prospects, but he did put scouts on notice with a terrific senior season. He made the transition from first base to the outfield this year, and hit .407 with 40 RBIs, 13 doubles and nine homers in 36 games.
He also contributed from the mound, finishing 6-0 with a 1.44 ERA. In his team's championship game, he threw a four-hit complete game and struck out 10. In four years on the varsity team, which his father, Jeff, coached, Carlson captured three championships.
Carlson will head to Florida on Thursday and start his development with the Rookie league Cardinals in the Gulf Coast League. The Cardinals plan to develop him as an outfielder, but he doesn't care where he plays at the professional level.
"I'm just going to play wherever the Cardinals put me," he said. "I just want to be in the lineup every day and play baseball."
Jenifer Langosch has covered the Cardinals for MLB.com since 2012, and previously covered the Pirates from 2007-11. Read her blog, follow her on Twitter, like her Facebook page and listen to her podcast. Nick Krueger is a reporter for MLB.com based in St. Louis. This story was not subject to the approval of Major League Baseball or its clubs.