Last month easyJet flew 3.9m passengers across its 500 routes compared with the same period last year when it flew 3.5m passengers.
EasyJet said the numbers were helped by the seven-day strike by British Airways (BA) cabin crew and the threatened strike by German carrier Lufthansa but that they were not a major factor.
“This is part of a strategy to grow our business by 10 per cent and to fly 50 million passengers,” said a spokesperson.
The airline also increased its load factor, or the number of seats it filled, by 87.5 per cent last month.
The news comes as discount rival Ryanair has seen a 13 per cent hike in passenger numbers for March, when it flew 5.3m customers as compared to the same period last year when it flew 4.9m passengers. In total, it flew 66.5m customers during the year ending 31 March.
Ryanair filled 79 per cent of seats on its flights, marking a two per cent hike from last year when it filled 77 per cent of its seats.
The numbers put both easyJet and Ryanair ahead of BA, which flew 2.2m passengers last month.
BA traffic dipped by 11 per cent as it said numbers were affected by the work stoppage launched by cabin crew, which cost the airline £40-45m.