New figures from the Central Statistics Office show that the number of passengers passing through the five main Irish airports - Dublin, Cork, Shannon, Knock and Kerry - were down almost 80% last year compared to 2019.
The CSO said that 8.3 million passengers passed through the main Irish airports last year.
This marked a drop of 78.2% on the more than 38 million passengers the previous year as Covid-19 restrictions hit international travel.
The CSO also said that 759,015 passengers passed through the main Irish airports in the fourth quarter of 2020, a fall of 91.1% over the same time in 2019.
Today's CSO figures show that more than 95,000 flights were handled by Ireland's main airports in 2020, a fall of 65.2% compared to 2019.
Dublin accounted for 84.5% of all flights, while Cork handled 6.8% of all flights.
London-Heathrow and Amsterdam-Schiphol were the most popular routes for passengers for Dublin airport in 2020.
For Cork airport, London-Heathrow and London-Stansted were the most popular routes.
The top route for Shannon and Knock airports was London-Stansted, while the top route for Kerry was London-Luton in 2020.
The CSO also said that the Irish airports handled a total of 138,787 tonnes of freight in 2020, the vast majority (93.8%) of which was international freight.
It said this marked a decrease of 11.8% in freight handled in 2020 when compared with the previous year.