Ryanair will open a base at London Southend Airport in April next year.
The low-cost airline announced it will operate 13 routes to eight countries from the Essex airport, including Barcelona, Corfu, Milan and Venice.
There will be more than 55 flights a week carrying an estimated one million passengers each year.
Three aircraft will be based at Southend, creating 750 on-site jobs per year, according to the budget carrier.
Ryanair chief commercial officer David O’Brien said: “Ryanair guests travelling to and from London and the Essex area can now enjoy low fares on a choice of 13 routes through London Southend’s exceptionally passenger-friendly terminal.
“Southend Airport’s train station will deliver direct services from the terminal to London Liverpool Street and also the new Crossrail service opening in 2019, making the airport even more accessible from all parts of London.”
The airport will be Ryanair’s 14th UK base.
Ryanair has previously warned that it will pivot growth away from the UK due to Brexit.
Mr O’Brien insisted the decision to open a base at London Southend should not be viewed as a “vote of confidence into the future of UK aviation”.
Almost a quarter of Ryanair’s capacity growth this year will be in Germany, compared with just 10% in the UK.
“You can see how (the UK is) beginning to lag within the Ryanair environment,” Mr O’Brien said.
He added that the closure of Ryanair’s base at Glasgow Airport at the end of the summer – announced in February – is due to its “remoteness”, decreasing demand and Air Passenger Duty.
Demand for flights from the UK to Europe is flat this year while passenger numbers from countries such as Germany, Italy and Spain are growing.
Stobart Group, which owns and operates London Southend, has been rocked in recent weeks by efforts from key shareholders to install retail boss Philip Day as chairman of the firm and boot out incumbent Iain Ferguson.
The infrastructure business is under pressure from former chief executive Andrew Tinkler, former director Allan Jenkinson and the fund controlled by star investor Neil Woodfood.
Mr Tinkler’s successor, Warwick Brady, was asked by reporters whether he is confident of being able to “carry on and deliver” the growth announced at London Southend.
He replied: “We’ve got a great management team. It’s going to give us the platform to grow and to generate cash and shareholder returns.
“Ryanair’s commitment to London Southend (shows) a real confidence in the management team and my leadership.
“I hope to see that lasting for many years to come.”