Eastern Airways is expanding its network from Southampton airport to six routes following the collapse of Flybe.
The airline will reconnect the south coast airport to Belfast City by taking over the former Flybe route from March 23.
Seven flights a week have been scheduled to Northern Ireland.
The former Flybe franchise partner has already moved to start services from Southampton to Manchester and Newcastle, both initially with 11 flights a week.
These are in addition to new route to Teesside airport with 11 flights a week.
The carrier will also offer a Southampton link to Aberdeen via Teesside from April 27.
Eastern Airways already provides up to 15 flights a week between Southampton and Leeds Bradford.
The new routes will give the airline up to 70 departures a week from Southampton and plans to base up to five aircraft at the airport “over time”.
General manager commercial and operations, Roger Hage, said: “We are ensuring Southampton is re-connected to the regions throughout England, Scotland and Northern Ireland.
“Initially the Belfast City route will be daily and reconnects the south coast of England to Belfast for business and leisure, while inbound passengers have the London rail connection within the hour and access to the major cruise offering via the port.
“By providing six destinations from Southampton, frequency and additional destinations will continue to increase.”
Southampton airport managing director Neil Garwood added: “Belfast has long been one of our most in-demand destinations, and importantly this will once again enable vital regional connectivity with Northern Ireland.
“We look forward to enhancing our route network further with Eastern Airways.”