More than one million passengers used Luton airport in May, a 15.7% rise over the same month last year.
It was the first time the milestone of a million passengers in a month has been reached before the start of the peak summer period.
New routes launched to Essaouira, Split and Bodrum by easyJet and Naples with Thomson Airways helped push up the numbers.
The growth is set to continue with three new Wizz Air routes opening this month to Iasi, Ohrid and Constanta.
The airport is embarking on a £100 million redevelopment to raise annual capacity from 12 million to 18 million passengers by 2026.
Chief executive, Nick Barton, said: “Last month was our busiest May ever. As we move into the busy summer season we are committed to ensuring that passengers enjoy the best possible experience – our £100 million redevelopment project will help us to deliver that.”