Aer Lingus Regional flew a total of 112,435 passengers last month - up 35% on the same time last year.
The regional service, operated by Stobart Air (formerly Aer Arann), saw strong demand for new routes introduced during the year.
April marked the tenth month of growth for the airline in a row.
The airline said that passengers flying to and from Dublin were up 50% with the Kerry-Dublin route seeing an increase of 38% in April compared to same month last year.
It said that total passenger numbers are up 14% so far this year compared to this time last year.