Three oil tanks have been transformed to create a flagship live art gallery.
Tate Modern converted the huge tanks - used to store a million gallons of oil when the venue was a power station - into a gallery space.
The underground area is part of a £200m extension, which should be finished by 2016.
Tate director Sir Nicholas Serota told Sky News: "Tate Modern has been an enormous success in showing painting, sculpture and installation.
"What we want to do is to extend that and show film, performance, live art - this is a really important part of the way visual artists work today.
"For the last 50 years they've been doing this, and Tate hasn't really been able to show it."
The raw industrial space is unique and offers exciting prospects for performance artists to share their work with a mass audience. It is the first permanent live art gallery space in the world.
For the next 15-weeks the gallery is offering an opening programme of live art and performance, including a film installation by Korean artist Sung Hwan Kim and dance by Anne Teresa De Keersmaeker.
De Keersmaeker is considered to be one of the most influential choreographers of late 20th century.
She said: "I don't think there is any other museum in the world where so many people come to have a new experience with art and somehow buy a ticket to the unknown.
"To have a live performance is creating the opportunity to have a different collective experience."
Since it opened in 2000, 56 million people have passed through Tate Modern's doors and it ranks as one of the top three tourist attractions in the country.
Its popularity has come as a surprise - annual attendances of five million far outstrip the two million initially expected.
It has revolutionised the way contemporary art is viewed. Now the question is whether it will do the same for installation and performance art.
Charlotte Higgins, chief arts writer at the Guardian, says it is too early to tell.
"You can hardly believe life without Tate Modern. Contemporary art was sneered at by most people or misunderstood, and you know now everyone has an opinion about Damien Hirst or Tracey Emin.
"Two years down the line we'll be able to say how significant these spaces are. At the moment it just looks like an exciting, intriguing prospect."
:: The Tanks 2012: 15 Weeks of Art in Action runs from July 18 to October 28.