Spanish-owned airports operator Heathrow Airport Holdings is to sell London Stansted Airport to Manchester Airports Group for STG1.5 billion ($A2.29 billion), it announced on Friday.
The deal means that the operator, formerly called BAA, will be responsible for just four British airports compared with its original seven.
London Stansted is Britain's fourth-busiest airport after London Heathrow, London Gatwick and Manchester.
"Stansted Airport and its people have been part of our company for a long time," said Heathrow chief executive Colin Matthews.
"It has been named by passengers as 'the world's best airport for low-cost airlines' for two consecutive years at the Skytrax World Airport Awards, and we are proud of its achievements.
"We wish the new owners every success and are confident the airport will continue to flourish. We will continue to focus on improving Heathrow, Glasgow, Aberdeen and Southampton airports."
The sale is expected to close by the end of February.