Ryanair saw an early summer spike in passenger carryings as the Covid-19 vaccine rollout sparked European travel recovery.
The no-frills airline group saw numbers rise to 5.3 million in June from just 400,000 in the same month last year.
More than 38,000 flights were operated with a 72% load factor.
The June total compares with 1.8 million carryings in May and one million in April to give a first-quarter total of 8.1 million passengers.
Rival Wizz Air carried 1.5 million passengers at a load factor of 64% in June against 502,000 a year earlier.
The Hungarian budget airline continued to grow its network with the opening of its sixth Italian base in Naples, offering 18 new international and domestic routes.
An additional Airbus A321 aircraft was also deployed to its Tirana base in Albania.
More: Ryanair takes delivery of first ‘gamechanger’ aircraft
Ryanair leads legal challenge against government travel traffic light system