Cromwell, who most recently starred opposite Minnesota native Jessica Lange in "American Horror Story: Asylum," is accused of disrupting a meeting of the UW Board of Regents.
The actor was allegedly protesting animal testing, and, along with another protester, held large signs featuring a cat with metal implanted in its head at a UW-Madison lab.
An official with the lab says federal agriculture officials have found their claims to be false, the Star Tribune reports.
Both Cromwell and the other protester were released from jail Thursday afternoon.
Cromwell, 73, has starred in such films as "The Artist," "The Green Mile," "L.A. Confidential," "Deep Impact" and "Babe" -- which earned him an Oscar nomination for Best Supporting Actor.
Cromwell also starred in the 2011 historical war drama "Memorial Day," which was shot in various parts of Minnesota.