The N-Dubz rapper was due to play the 4Music stage at the shows in Chelmsford and Staffordshire on August 18-19, but has been removed from the bill for unspecified reasons.
The Charlatans have been confirmed as Dappy's replacement on both days of V Festival 2012 and will take to the 4Music stage instead.
Meanwhile, LMFAO have announced that they will be playing the music event. The duo pulled out earlier this week due to illness, but have now told organisers the show will go ahead.
The Killers and The Stone Roses will headline the two-day festival, while Nicki Minaj, Noel Gallagher, Snow Patrol and Cher Lloyd are all set to play.
Watch the music video for The Charlatans' 'The Only One I Know' below: