The annual Pride parade in the capital, held in June, attracted hundreds of thousands and went ahead despite the country's parliament voting to ban the event at the urging of nationalist Prime Minister Viktor Orbán.
Budapest City Hall chose to join as a co-organizer on the grounds that the police cannot ban a municipal event.
On Wednesday, Karácsony was charged, according to the prosecution, with "organizing and leading a public event despite a ban issued by the police," The Guardian reports.
Viktor Orbán and his government have long faced harsh criticism abroad for enacting laws aimed at restricting the rights of LGBTQ people.
