Molina, a nine-time All-Star, took part in a game played at the team's complex in Jupiter, Florida, that included players who didn't travel for the Cardinals' 9-5 win over the New York Yankees in Tampa.
"Yadi caught Miles, threw a couple guys out, took his at-bats, so favorable positive day back on the ranch so to speak," manager Mike Shildt said. "They got their work in. It's a good day for the Cardinals."
The 36-year-old Molina has not played in a spring training game. He has averaged 133 games behind the plate over the past three seasons.
Mikolas went 18-4 with a 2.83 ERA and was an NL All-Star last season.