TMZ cited law enforcement sources it did not name as saying Ronson, 33, was pulled over by police for speeding as she drove home from Las Vegas Monday morning after working at the Lavo nightclub in the Palazzo hotel.
She failed a field sobriety test, refused to submit to a breathalyzer and was arrested, TMZ said.
The musician blew over the legal blood-alcohol limit when she finally took the breathalyzer test at the police station where she was booked, the report said.