The national carrier will operate the flights from the fourth quarter of this year onboard a Boeing 777-300 ER.
The route has been supported by Prime Minister David Cameron after he signed a deal to double trade between the UK and Indonesia by 2015.
“We want to link Britain up with the world’s fastest growing economies. And good air links are vital to achieving that. This new route from London to Jakarta is good for British business and will help them to compete in the global race,” he said on the announcement.
Stewart Wingate, chief executive at Gatwick said the new route was part of its strategy to target and sign-up routes to the emerging economies, which has also included China, Russia, Turkey and Vietnam.
Garuda has also launched flights to Auckland and Brisbane and has a codeshare deal in place with Etihad Airways.