A total of 36.5 million passengers passed through the main Irish airports last year, an increase of 6.1% over the previous year.
New figures from the Central Statistics Office show that passenger numbers increased last year in Cork, Dublin, Kerry, Knock and Shannon airports.
But passenger numbers decreased in airports in Connemara in Galway and Inishmore in Donegal.
The CSO said the five main airports accounted for 99.8% of all air passenger numbers, while Dublin airport accounted for 85.6% of all air passengers carried in 2018.
Meanwhile, over 8.4 million passengers passed through the main Irish airports in the fourth quarter of last year, an increase of 6.9% over the same time in 2017.
Today's CSO figures show that more than 266,000 flights were handled by the main airports in 2018 with Dublin accounting for 83.6% of all flights, while Cork handled 7.7% of all flights.
London-Heathrow and London-Gatwick were the most popular routes for passengers for Dublin airport in 2018.
For Cork airport, London-Heathrow and London-Stansted were the most popular routes.
The top route for Shannon was London-Heathrow, while the top route for Knock was London-Stansted and the top route for Kerry was London-Luton in 2018, the CSO noted.
The main Irish airports also handled a total of 157,364 tonnes of freight in 2018, the vast majority (93.6%) of which was international freight.