The number of passengers flying with easyJet increased by 11.3% in June to 7.7 million.
The airline saw the passenger load factor rise by 0.8 percentage points over the same month last year to 94.8%.
The June performance gave easyJet a rolling annual passenger total up by 8.7% to 78 million with a load factor of 92.1%.
Meanwhile, budget rival Norwegian hit a new milestone in June by flying more than 3 million passengers in a single month.
The number represented a 10% rise over the same month last year, with long-haul routes seeing a 38% rise in carryings.
Norwegian’s average load factor for June was 90% with long-haul aircraft seeing a load factor of 95%.
Chief executive, Bjørn Kjos, said: “We reached several milestones this month, both in terms of passenger numbers and fleet renewal.
“I’m very grateful that more than 200 million passengers have shown confidence in us and chosen to fly with Norwegian since we began in 2002.
“Over the past few years, our growth has been driven by our long-haul routes, and this will continue.”