The new build will help secure the long-term future of both the show and the site, with completion expected in 2018.
The set will provide a modern, upgraded exterior filming resource for EastEnders, and will copy the appearance of the existing buildings.
However, it will be 20% bigger than the current set, in order to enable greater editorial ambition and improve working conditions for staff.
A temporary set will be created on site to enable filming to continue while the permanent structure is rebuilt.
"This is a really exciting project and firmly demonstrates the BBC's commitment to the future of EastEnders," said executive producer Dominic Treadwell-Collins. "We have ambitious plans for the show, and the new exterior set will help bring those to life and better reflect the East End of London on screen for audiences.
"The bigger and improved set will increase the potential for storylines, increase quality and meet the demands of future technology requirements. Crucially, it will provide a greater sense of scale with more locations for our characters to spend time in, opening up new areas and opportunities that haven't been possible before – all of which are in the best interest of our viewers."
Kate Harwood, head of Drama England at BBC Drama Production, added: "I'm glad the BBC Executive Board has agreed that this project is crucial to investing in the future of EastEnders. The improvements and modernisation are vital to the growth and development of the show.
"As we approach the show's 30th anniversary, this is a really exciting opportunity to underpin the future of one of the BBC's most important programmes."
It is expected that work will begin at BBC Elstree later this year, followed by the start of the construction works for the temporary set in early 2015.
Digital Spy Soap Scoop video - hit play below for gossip on Sarah's Coronation Street return, Kat's devastating decision in EastEnders, Laurel's problems exposed in Emmerdale and a turn to the dark side for Darren in Hollyoaks.