Ryanair is to begin flights in October from George Best Belfast City Airport to three destinations in Great Britain.
Aer Lingus and Ryanair are due to begin new Belfast routes
The budget airline announced daily flights to Liverpool, Glasgow and the East Midlands, but promised routes to mainland Europe within the next year.
And Aer Lingus is to fly from Belfast International to London Heathrow in August, the BBC has learned.
It is understood there will be four daily each way flights.
The new route emerged as negotiations continued for Belfast International to become the airline's UK hub airport.
Ryanair, which already operates from City of Derry airport, said it would sell the first 10,000 tickets on the Belfast routes for £10, including taxes and charges.
Announcing the new services, spokesman Peter Sherrard said the airline was planning to expand its Belfast operation.
"We haven't decided which airports we're going to yet, but we expect to announce it in the next 12 months," he said.
Budget rival Easyjet already operates flights from Belfast International to Glasgow and Liverpool, while bmibaby has an East Midlands route.