EasyJet passenger numbers rose 19.1 per cent in January compared with the same month last year.
More than 3.74m people took to the skies with the carrier last month, up from 3.14m in January 2010.
But the load factor, which measures how well planes are filled on average, dropped from 79.3 per cent to 78.9 per cent.
The number of travellers flown over the past 12 months rose 8.5 per cent to 50.32m.
The load factor over that period was 87.1 per cent up from 86.2 per cent.
Its shares slumped to a three-month low a few weeks ago after the company admitted snow and strike disruption cost it £31m in the last quarter of 2010.
Soaring fuel costs will also hit its results this year, it said.