The man was arrested at Brindisi airport in the south of country, after going to the toilet between the plane and the terminal building.
He was believed to have been travelling for a holiday in the city of Lecce on the service with the low-cost airline which departed from Manchester.
The holidaymaker was described as being in a state of “mild agitation” as he left the plane before relieving himself in front of more than 50 fellow passengers, Metro reports.
He was later arrested police and has since been fined £2,700 for “acts contrary to public decency”.
A Ryanair spokesman told Metro: “An individual was detained by local police at Brindisi airport on September 30. This is a matter for local police.”
