Maverick Sabre, Kurt Vile and Howler have also been added to the festival, which takes place in Spain from July 12 to July 15.
They join a lineup which already includes Noel Gallagher's High Flying Birds, Florence + the Machine, Example, The Vaccines and Katy B.
The Stone Roses will also headline a day at the music event as part of their extensive world tour, following their reunion last October.
Tickets for Benicassim 2012 are on sale now through the festival's official website.
Dizzee Rascal recently released a free mixtape titled Dirtee TV after signing an "unprecedented multi-layered deal" with Universal Music last year.
> Dizzee Rascal: 'I wasn't pressured into going pop'
Watch the music video for Dizzee Rascal's 'Holiday' below: