Stephenson, 18, is from Kennesaw Mountain High School in Georgia. He casts a large shadow at the position at 6-foot-4 and 225 pounds, and he has drawn comparisons to Orioles catcher Matt Wieters.
• 49th overall: Antonio Santillan
• 71st overall: Tanner Rainey
A right-handed hitter, Stephenson batted .415 with eight home runs and 25 RBIs for Kennesaw Mountain this spring.
"We're very excited," Reds senior director of amateur scouting Chris Buckley said. "He's a guy we've followed since last summer. We're thrilled to have him."
The Draft continues on Tuesday. The MLB.com preview show begins at 12:30 p.m. ET, with exclusive coverage of Rounds 3-10 beginning at 1 p.m. ET.
Ranked the 18th overall prospect in the Draft by MLBPipeline.com, and the top catcher, Stephenson was viewed as a possible overall No. 1 pick throughout the spring. That honor went to Vanderbilt University shortstop Dansby Swanson, who was taken by the Diamondbacks.
Buckley was not surprised that Stephenson was still on the board, however.
"Sometimes certain people are a little more afraid of catchers," Buckley said. "We thought he would go in around where we picked."
And Stephenson was not disappointed as he watched the Draft at home with his family, friends and excited high school teammates.
"They dogpiled on me. It was awesome," Stephenson said. "It's everything you can possibly imagine. The Reds, you can't beat it. Great ballpark. Great city. … It's a dream come true."
The bonus for the 11th overall pick has a slot value of $3,141,600 for Cincinnati. Stephenson already has a college commitment to Georgia Tech should he not turn professional, but he seemed eager to start his pro career.
"I'm hoping to kind of get it over with and kind of sign and see what holds in the future," Stephenson said.
Stephenson garnered some added attention last month for his team when video of him flipping his bat on a home run went viral. He had been intentionally walked in his three previous plate appearances that night.
• Cut4: Stephenson executes majestic bat flip
"I didn't think it would be this crazy," Stephenson said. "I didn't know it'd be this worldwide known. We ended up playing the team that knocked us out last year in the playoffs. We were playing them again. They were talking a whole bunch of smack -- it's high school baseball. I mean, the emotions kind of picked up, and the bat flip kind of happened."
This is the fifth time the Reds have taken a catcher in the first round of the Draft. More recently in 2007, Cincinnati picked Devin Mesoraco out of Punxsutawney High School in Pennsylvania with the 15th overall pick. In 2010, Yasmani Grandal from the University of Miami was taken 12th overall. Although on the disabled list, Mesoraco is now the primary catcher for the Reds since he broke into the big leagues in 2011. Grandal is currently in the Majors with the Dodgers.