The Cardinals also announced that right-hander Alex Reyes is going to have shoulder surgery later this month.
The 27-year-old Reyes met with Dr. Neal ElAttrache in Los Angeles on Monday. He wanted a second opinion about his ailing shoulder that has kept him on the injured list all season.
The move with the veteran catcher comes one day after Molina made his first career pitching appearance, working the ninth inning of an 18-4 victory at Pittsburgh. He allowed a pair of homers and four runs while finishing the Cardinals' three-game sweep.
The 39-year-old Molina is batting .239 with two homers and eight RBIs in 26 games in what likely will be his final big league season.
Rookie catcher Ivan Herrera was recalled from Triple-A Memphis. The 21-year-old Herrera, one of the organization's top prospects, is looking to make his big league debut.
Reyes was shut down this month after he experienced renewed shoulder soreness.
Reyes has battled injuries for several years. Tommy John surgery in 2017 cost Reyes the most time on the injured list, but his shoulder also has been a consistent source of concern for the last few years.
From 2016 to 2020, Reyes pitched just 72⅔ innings. He was made a full-time reliever last year, and he posted a 2.48 ERA in 72⅓ innings.
Reyes converted his first 22 save opportunities in 2021 before soreness and wildness in the strike zone resulted in him eventually losing his closer job to Giovanny Gallegos. Reyes surrendered Chris Taylor's game-ending homer in the NL Wild Card Game against the Los Angeles Dodgers.
Reyes, who turns 28 in August, has a $2.85 million salary this season in the second of three arbitration-eligible years.
Also Monday, the Cardinals placed left-hander Steven Matz on the 15-day injured list because of shoulder impingement and outfielder Dylan Carlson on the 10-day injured list because of a left hamstring strain.
Matz lasted only four pitches Sunday in his start against the Pirates before being pulled with stiffness in his left shoulder. It has been an up-and-down season for Matz, a free-agent addition this offseason from the Toronto Blue Jays. He entered Sunday with a 3-3 mark and a 6.03 ERA.
Carlson, who is hitting .247 with two home runs and 11 RBIs in 39 games this season, was placed on the IL retroactive to Saturday.
The Cardinals also optioned Angel Rondon (1-0) to Triple-A Memphis on Monday. Rondon allowed just one hit in five innings in relief of Matz on Sunday for his first win in the majors, striking out four and walking three.
In addition, the Cardinals recalled left-hander Matthew Liberatore and outfielder Lars Nootbaar from Memphis. Liberatore, one of the Cardinals' top prospects, made his major league debut Saturday against the Pirates. He allowed four runs on seven hits with three strikeouts and two walks in 4⅔ innings during that start.
The Associated Press contributed to this report.