The man was charged with “wrongful boarding of a ship”, “unlawful entry into a restricted area”, and refusal to provide his fingerprints when detained.
The migrant, who had been in Calais for a few months, denied being a ringleader, saying he just followed the group of migrants who broke into the harbour area and then boarded the “Calais Seaways” ferry which had just arrived from Dover in England.
He was tried and sentenced in the nearby northern French town of Boulogne.
A total of 63 migrants were detained in the incident late Saturday, many of whom had tried to hide aboard the Danish-operated DFDS ship, regional authorities said.
On Sunday morning, firemen talked down the last of the migrants who had climbed high above the deck to a walkway attached to the ship's funnel.