Nootbaar exited Monday's loss to the Kansas City Royals after slamming into the wall catching a drive in the second inning then pulling up while chasing a hit in the third.
He had not played since Monday, and the IL move for a lower back contusion is retroactive to Tuesday.
The Cardinals recalled rookie outfielder Jordan Walker in a corresponding move.
Walker started the season on the major league roster but was sent down to Triple-A Memphis after going 7-for-35 over a 10-game stretch.
Nootbaar is hitting. 266 with four home runs and 21 RBIs this season. He missed two weeks after jamming his left thumb on Opening Day.
Walker, a first-round pick out of high school in 2020, was hitting .274 with two home runs and 11 RBIs for the Cardinals prior to his demotion.