A crime report filed under Rihanna's real name, Robyn Fenty, confirmed that the singer is the complainant in the alleged domestic violence felony committed by Brown.
A representative for the star had originally claimed that a "traffic mishap" was behind her nonappearance at the Grammy Awards.
TMZ reports that the 20-year-old was left bruised following the incident, which is claimed to have taken place in LA in the early hours of Sunday morning.
An eyewitness told website radaronline that Rihanna arrived at Cedars-Sinai hospital with police and sought treatment.
"Rihanna was clearly very upset by what had happened and I could hear her screaming", the onlooker claimed. "Rihanna was trying to get her point across about something, she sounded like she was crying as she tried to get her point across."
Representatives for Brown have yet to comment on the alleged incident. In a statement, Rihanna's publicist later said that her client was "well" and thanked fans for their "concern and support".