Ryanair said it carried a total of 7 million passengers in January, up from 1.3 million the same time last year.
The airline said it operated over 46,400 flights in January with a load factor - how many seats it fills on each flight - of 79%. This was up from 69% in January 2021.
Ryanair noted that its passenger numbers were badly affected by the travel restrictions imposed because of the Omicron variant of the coronavirus in both December and January.
Earlier this week the airline reported a loss of €96m for the final three months of 2021 but said it was hopeful that rivals' cuts to capacity may help push prices up in the key summer season.
The result was in line with a consensus estimate of a €101m loss in a company poll of analysts.
The airline lost €306m in the same quarter of 2020 and made a profit of €88m in the last three months of 2019.
Its group chief executive Michael O'Leary said that while there had been a "very strong bounce back" in bookings in recent weeks as concerns about the Omicron variant began to fade, the outlook remained hugely uncertain.
