Ryanair flew almost 6.7m passengers in March, according to the airline, up 28% on the same month of 2014.
The airline filled 90% of its seats during the period – compared to 80% in March of last year.
The figure brings to 90.5m the total number of passengers Ryanair carried in the year to March 2015.
The airline said the increase was due to lower fares, better service and an improved forward booking strategy.
Ryanair’s figures would also have been aided by a number of sporting events which took place during the month, including a number of Six Nations rugby fixtures.