In late May, the 28-year-old prince, the nephew of Belgian King Philippe, went to two parties in the southern Spanish city of Cordoba and tested positive for the new coronavirus two days later.
The government in Andalusia province has fined him 10,400 euros ($11,850) for breaking the 14-day quarantine that all arrivals in the country must observe, the EFE news agency said.
The Prince reportedly has 15 days to voluntarily pay half of that sum or contest the penalty. He had previously admitted his guilt in a statement shared by his lawyer.
Local media said earlier that he went to a party along with 26 other people, which was above the 15-person cap for gatherings. It was later revealed they were two separate parties of 12 and 15 people each.