Aer Lingus made an operating profit of €40m in the first six months of the year, a turnaround from the €83m loss it recorded the same time last year.
Its passenger revenue for the six months to the end of June rose by 60% to €976m.
The improved Aer Lingus performance was driven by the US markets and a recovery in the shorthaul European leisure destinations, its parent group IAG said.
Aer Lingus said the positive half year performance demonstrated an increased seasonality in the business with a first quarter operating loss of €81m offset by a €121m operating profit in the second quarter.
The airline said the momentum achieved in the second quarter of 2023 was based on strong leisure performance on both our long haul and short haul network.
"We have rebuilt our capacity to pre-pandemic levels, and expanded our transatlantic routes and frequency, offering the largest ever number of seats to North America in 2023," the airline said.
"As part of our long haul programme we began operating a new route to Cleveland, Ohio and recommenced flying to Hartford, Connecticut," it added.
Short haul routes to Europe also performed strongly in the three months from April to June, with the sun destinations in high demand.
"While leisure travel has delivered strongly, business travel has not yet fully recovered, emphasising the key importance of the summer peak to the business," the airline said.
"We are particularly looking forward to the arrival of fans in huge numbers for the Aer Lingus College Football Classic match between Notre Dame and Navy which is taking place on Saturday 26 August 2023 in the Aviva Stadium," the airline said.
It is expecting more than 40,000 international travellers, which will make it the largest ever movement of US citizens to another country for a major event.
The airline's parent IAG said its quarterly profit beat analyst forecasts by 40% and said the outlook for summer travel was encouraging, although it warned it was "mindful" of uncertainty in the wider economy.
