Zimmermann was supposed to be Baltimore's starter Friday night against Toronto, but the Orioles instead will go with right-hander Thomas Eshelman. They selected Eshelman's contract from Triple-A Norfolk.
Baltimore also designated catcher Chance Sisco for assignment.
Zimmermann is 4-4 with a 4.83 ERA this year. His move to the IL is retroactive to Tuesday.
Cisco has hit .154 in 23 games in 2021.