The airline is also set to cease services from Belfast City Airport at the end of autumn, which will mean it no longer has any routes serving Northern Ireland.
“It is disappointing that Ryanair has now decided to withdraw operations from the entire Northern Ireland market at the end of October, having variously had a presence in all three local airports in recent years,” a spokesperson for Belfast International Airport said.
The spokesperson added that the airport has been in talks with airlines, including some that currently do not fly to or from Belfast, to take over some of the routes previously flown by Ryanair.
“To this end, we hope to be able to make announcements regarding fresh route development in the near future,” the spokesperson said.
Irish broadcaster RTE said Ryanair did not respond to requests for an explanation of the reasoning behind the latest decision.