Emerald Airlines has been awarded a contract by the Government to operate the Dublin-Donegal public service obligation (PSO) route.
The new carrier, which recently won a ten-year contract to run the Aer Lingus Regional service, will run the PSO route under the Aer Lingus brand.
The route has been operated on a temporary seven-month basis by Swedish airline, Amapola Flyg AB, since the collapse of the previous contract holder Stobart Air in June.
Amapola's interim contract will expire on February 25, at which point Emerald will take over and run the service for three years.
The deal includes an option for a further one-year extension at that point.
The service will include up to two flights each day between the capital and Donegal.
The airline will use a 72-seat ATR72-600 and will fly under Aer Lingus flight numbers.
"We are delighted to have been chosen as the new operator of the vital air route between Donegal and Dublin for the next 3 years," said Emerald Airlines CEO, Conor McCarthy.
"This announcement is a great boost for ensuring continued connectivity from Donegal to Dublin, and beyond, and we are really looking forward to welcoming passengers onboard from 26 February next."
Emerald won the contract following an EU public tendering process conducted by the Department of Transport.
"Government funded air services on the Donegal to Dublin route provide vital connectivity for Donegal and the North-West region to Dublin," said Minister for Transport, Eamon Ryan.
"I know that this route provides important reassurance for those who need to attend medical or other important appointments as well as supporting business and tourism in the region."
The development was welcomed by Donegal Airport.
"The ATR72-600 series aircraft, operated by Emerald Airlines, will also provide additional seat capacity on the route which will help the Airport regain passenger numbers post Covid-19 and contribute to our working closely with business and tourism development agencies to further promote the region as an attractive destination," said Steve Ó Cúláin, Chairman, and Eilís Ní Dhochartaigh, Managing Director of Donegal Airport in a statement.
Last month, Emerald Airlines said it would start operating Aer Lingus Regional flights in March - 10 months ahead of schedule.
Emerald Airlines plans to fly over 340 flights per week across 11 routes from March 17.