New figures from Dublin Airport reveal that a record 1.2 million Northern Ireland residents used the airport in 2015, a 37% increase on the previous year.
Dublin Airport also set a new record as a gateway to Northern Ireland for overseas visitors last year.
An estimated 1 million overseas residents used Dublin Airport to travel to and from Northern Ireland last year.
The big increase in passengers from Northern Ireland was due to a further expanded route network with 23 new services and extra capacity on 40 existing routes at Dublin Airport last year.
Dublin Airport is also growing its importance as a key international gateway for overseas visitors to Northern Ireland.
67% of all passengers who came by air to the island of Ireland travelled via Dublin Airport last year, the airport's chief communications officer Paul O'Kane noted.
Today's figures also show that half of Northern Ireland residents used Dublin Airport for holiday trips last year, with 26% flying from Dublin on their main holiday and a further 24% using Dublin for an extra holiday.
Business travel accounted for 11% of trips and 20% of passengers were visiting friends or relatives.
Three quarters of all passengers from Northern Ireland take a direct flight from Dublin to their final destination with about one-quarter making onward connections at another airport.
The UK continues to be the most popular country destination for Northern Ireland passengers using Dublin Airport followed by the US, Spain, Germany and France.
Total passenger numbers at Dublin Airport have increased by 12% to more than 18.8 million in the first in the eight months of this year. Last year the airport hosted a record 25 million passengers.