AER Lingus carried 734,000 passengers in December, an increase of 7.2pc from a year earlier, new figures published today show.
It flew 9.65 million passengers in 2012, up from 9.51 million a year earlier.
Revenue per passenger gained 3.4 per cent in 2012.
Short haul flown passengers, including Aer Lingus Regional, in December 2012 were 658,000, an increase of 6.5 per cent on December 2011, while long haul flown passengers in December 2012 were 76,000, an increase of 13.4 per cent on December 2011.
Meanwhile, EasyJet carried 6.7 per cent more passengers in 2012, after the airline boosted frequencies on key routes and introduced allocated seating.
EasyJet carried 59.2 million people in 2012, up from 55.5 million in 2011, the Luton, England-based company said in a statement today.
The number of seats filled as a proportion of those available for the year was 88.9 per cent.
Chief executive officer Carolyn McCall has increased the number of daily flights on key routes while using allocated seating, flexible tickets and corporate agents to grab a bigger slice of the business market.
The airline carried 4.3 million passengers in December, up from 4.1 million a year earlier.
Ryanair, Europe's biggest discount airline, is set to post annual traffic figures later today.
Meanwhile, Ryanair said passenger numbers grew 2pc in December year-on-year, as it carried 4.8 million passengers.
Europe's largest low-cost airline also said on Monday its load factor - a measure of the proportion of seats sold - rose to 81pc from 79pc a year ago.