Luton flights have previously been from Belfast International, but easyJet is now assessing if passengers would prefer an airport closer to Belfast when flying on shorter routes.
Trevor Spinks, the airline’s commercial manager for Northern Ireland, said: “People have made us Northern Ireland’s favourite airline, but we are always looking for ways to improve our service.
“We are testing the water on the Luton route. With fares from only £21.99 including taxes, bookings so far have been excellent and, if the trend continues, we may provide more flights.
“We would also consider introducing additional routes from Belfast City over time.”
Overall, easyJet will remain the leader in offering an unbeatable package for London travellers, with flights to Gatwick and Stansted continuing to operate from Belfast International.
Spinks added: “easyJet is No 1 in the region but we remain very committed, not complacent.
“We will take our time in assessing the feedback from Luton passengers and then decide how best to configure our operations between the two Belfast airports in the longer term.
“In the meantime, I know that people will appreciate the convenience of our Luton service.
“Luton is less than an hour from the centre of London. Business people can quickly get down to work in the City – and leisure travellers can enjoy the great shops and shows.”
Brian Ambrose, chief executive of George Best Belfast City Airport, said: "We are delighted that easyJet has selected Luton as its first destination from Belfast City - a route we currently do not offer and one I know will be popular.
"We are particularly pleased that our first easyJet passengers were able to avail of our new security area and our new enhanced departures lounge, which both opened before Christmas and have proved exceptionally popular.
“I am certain that the continuing private investment by our owners in the airport’s infrastructure, aimed at enhancing the customer experience, will appeal to easyJet’s passengers.
“The arrival of another premier airline to Belfast City will be welcome news for our growing customer base.”