Campus police say they were called to the complex just before 11 p.m. on Friday night to break up a fight and arrested McQuillan after finding another man suffering from what the police report described as "significant facial injuries."
Police have not released the victim's name.
McQuillan, who would be a fifth-year senior next season, is charged with second-degree assault and disorderly conduct. He is free after posting a $500 bond and is due back in court on May 21.
He started 11 games last season. He caught 16 passes for 158 yards and a touchdown.
UConn spokesman Mike Enright says the athletic department is aware of the incident.