The dance duo will headline the Slam Tent at the music event, which takes place in Balado, Kinross-shire in Scotland between July 6 and 8.
Paul Kalkbrenner, Gary Beck and Hans Bouffmyhre will also play the tent on the Sunday, with DJ Yoda playing the stage on the Saturday.
The Stone Roses, Kasabian and Snow Patrol have been confirmed as the headline acts for T In The Park 2012.
Tinie Tempah, Cher Lloyd, Noel Gallagher, Florence + the Machine, Emeli Sandé, The Vaccines, Childish Gambino and Cover Drive will also perform at the three-day event.
Tickets for T In The Park 2012 are on sale now.
Watch the music video for Orbital's new track 'Straight Sun' below: