Closed-circuit television footage showed a portly figure wearing an ill-fitting costume including gloves, cape and mask, bringing a 27-year-old man to a police station in Bradford in northern England.
The suspect was arrested and charged with handling stolen goods and fraud-related offences, said the force. But the costumed crime-fighter disappeared into the night without leaving his name.
"The person who brought the wanted man into the station was dressed in a full Batman outfit," said a spokeswoman for West Yorkshire Police. "His identity, however, remains unknown."
The suspect was handed over in the early hours of February 25, said police who released photos of the footage this week.