Ryanair will open a new base at London Southend, from April 2019, with three based aircraft at the airport.
The carrier said it represented an investment of $300 million.
The low-cost airline will operate and 13 new routes to eight countries, including Alicante, Barcelona Reus, Bilbao, Brest, Corfu, Cluj, Dublin, Faro, Kosice, Malaga, Milan Bergamo, Palma and Venice.
Ryanair hopes the move will deliver one million guests annually to London Southend Airport.
Ryanair chief commercial officer, David O’Brien, said: “We are pleased to add London Southend Airport to our UK base network.
“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 St and also the new Crossrail service (opening in 2019), making the airport even more accessible from all parts of London.
Warwick Brady, chief executive of airport owners Stobart Group said: “We are delighted to welcome Ryanair and its guests to London Southend in summer 2019.
“We have a clear and focused strategy to grow our airport to welcome over five million passengers a year by 2022.
“We look forward to delivering a great service to Ryanair guests to ensure we support the extraordinary growth of Ryanair operations out of London.”
London Southend Airport is an established airport serving business and leisure passengers flying across Europe.