Taveras, a 21-year-old outfielder, was batting .325 in 49 games with Memphis with seven homers and 40 RBIs. He will take the place of Matt Adams, who was put on the disabled list with a left calf strain.
"You know what I'm supposed to do is downplay it, right?" manager Mike Matheny said before Saturday's game. "I'd be lying to you to say I wasn't excited for him."
The 21-year-old Taveras didn't downplay it, either. This is his first look at Busch Stadium.
"Oh, man," he said before the game, "I'm so happy. I know when I hit for the first time, with the fans, it'll be awesome for me."
Taveras batted sixth and played right field. He got a standing ovation before flying out to left to end the second.
"We've got enough very, very good players that we're not going to rely on him to shoulder this," Matheny said. "I do believe he can be an addition to something good.
"We've got an opportunity for a couple weeks to see what this kid can do."
Taveras was ESPN MLB analyst Keith Law's No. 5 prospect for 2014 and No. 2 for 2013.
Cardinals senior vice president and general manager John Mozeliak said the move was made when they found out Adams would not be available for a couple more days.
"It made sense in two ways," Mozeliak said. "One, let Matt Adams heal, and two, it's an opportunity to give Oscar some playing time and not have to worry about the balance of power and worry about who's playing and who's not."
The Cardinals signed Taveras in 2008 out of the Dominican Republic. Before this season, Taveras was ranked as the No. 3 overall prospect by MLB.com and Baseball America. He has a career .321 average over six minor league seasons.
The Associated Press contributed to this report.