UK-based Stansted Airport served 18 million passengers during the 2013 fiscal year, showing a 3.4% increase in annual passenger numbers compared with the previous year.
The airport crossed the 18 million passenger mark for the first time since December 2011.
Air transport movements during this period increased 1.4% year-over-year to 131,344, while cargo tonnage decreased 6.5% to 205,220t.
Growth in the passenger number was driven by the busiest April experienced by the airport since 2008 with approximately 1.72 million passengers passing through the terminal, an increase of 10.7% compared with the corresponding period last year.
According to the airport, the increase can be attributed to the later Easter holidays this year and several new routes launching from the airport.
Air transport movements in April decreased 4.2% year-over-year to 12,089, while cargo tonnage fell 15% to 16,148t.
Stansted managing director Andrew Harrison said: "To see Stansted experience its busiest April for six years, and to once again break through the 18 million passengers a year barrier, is a key milestone in our growth plans for the airport, which are already providing people with more choice of destinations and increased flight frequency.
"We are also continuing our work to develop long-haul services from Stansted, and were delighted by the recent announcement that Thomas Cook is to launch new services to the US and Mexico next year.
"The level of growth we're seeing is encouraging and strongly believe Stansted has a vital role over the next ten to 15 years in supporting economic growth and activity."
The airport is currently waiting for the UK Government's response to the Airport Commission's recommendations on how to make the best use of its existing capacity before any new runway can be built.