New transatlantic routes contributed to 9.2% year-on-year growth in passengers using Stansted last month.
The total rose to more than 2.5 million in May with the first full month of operation of Primera Air’s new A321neo routes to New York, Toronto and Boston as well as Wow Air’s new Reykjavik service.
The airport expects this month to be busier, following the start of Emirates’ daily Boeing 777-300ER service to Dubai.
Manchester airport’s traffic was flat in May at just under 2.5 million passengers over the same month last year.
Growth is expected to return during the summer as airlines fill slots vacated by Monarch Airlines, which ceased trading last October.
The airport announced two new long-haul destinations in May, with Addis Ababa by Ethiopian Airlines and Mumbai by Jet Airways.
East Midlands airport grew 2.6% year-on-year to handle 517,000 passengers in May as new summer links to Seville and Egypt proved popular.
Together, the figures mean the UK’s largest airport group grew 3.9% in May to serve a record 5.5 million passengers.
MAG airports, with their spare runway capacity, are seen as playing a vital role in supporting aviation growth in the UK in the period before any new runway at Heathrow is opened.
Stansted chief executive Ken O’Toole said: “London Stansted continues to go from strength to strength, and our busiest ever May and the exciting arrival of one of the world’s truly global airlines in Emirates, is further evidence of our ambition to attract more airlines and play a key role in delivering the expected growth in the London market over the next decade.
“Last week the government announced its support for UK airports looking to make best use of existing runway capacity.
“This support is a very welcome as it’s vital for the economy that the country has the best possible international connections and that there is an urgent need to actively support airports, like London Stansted, that can deliver that access now.
“We know that we have even more potential, not only as an economic driver for the region but also by providing greater international connectivity to UK plc.”