Low-cost airline easyJet has secured a new 10-year deal with Luton Airport which could see it double in size at the site from four to nine million passengers a year.
It said the expansion would also see 2,500 jobs created at the airport and in the surrounding region.
But chief executive Carolyn McCall said the pace of the growth was dependent on improvements to the site being approved, adding that Luton could make a "real and immediate" contribution to the need for more airport capacity.
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Easyjet has 15 aircraft based at the site, its second largest base in the London area, and employs 1,600 staff locally. It says it plans to grow capacity by 20% over the next year.
The airline says it will do this by adding new business and leisure routes and increasing frequencies from some of its existing 39 routes.
Ms McCall said: "This is a substantial, long-term deal with London Luton Airport - our first base and the airline's home - which will enable us to double our size at London Luton in the next decade and add an even greater range of business and leisure destinations.
"The speed of easyJet's expansion at London Luton is in part reliant on the airport's plans for much-needed improvements being approved.
"Those improvements will unlock the airport's potential by improving the customer experience of the airport while also increasing the numbers of passengers flying to and from London Luton.
"This will in turn drive economic growth and jobs for the region."