He had been out since jamming his left thumb on a headfirst slide into third base on Opening Day on March 30. Nootbaar is in the starting lineup, batting seventh and playing center field, for Saturday's game against the Pittsburgh Pirates.
"It's good to have him back in the lineup," Cardinals manager Oliver Marmol said. "This is a guy that obviously is good at several things performance-wise, defensively, offensively, on the bases, but also brings a ton of energy and some of the intangibles that he brings to the team are welcomed."
Nootbaar, 25, batted .228 with 14 home runs and 40 RBIs in 108 games with the Cardinals last season and was 1-for-4 with a run scored and two walks to start this season. He went 0-for-5 in a rehabilitation appearance as a designated hitter with Double-A Springfield on Thursday before testing his thumb in drills Friday in St. Louis.
"There's still some soreness, and that's mainly coming from the defensive side," Nootbaar said. "That's kind of like a tolerance thing, but I think we'll be all right."
To make room on the 26-man roster, St. Louis optioned Juan Yepez to Triple-A Memphis. Yepez, 25, appeared in three games for the Cardinals and batted .333 with one home run and one RBI.
Reuters and The Associated Press contributed to this report.