The dance duo top the bill on the second stage on Sunday night at the festival, which takes place from September 6-9 at Robin Hill Country Park, Isle Of Wight.
The theme for this year's festival has been announced as Wildlife.
Organiser Rob da Bank confirmed that he would be announcing one act a day over the next fortnight leading up to a major announcement in mid-February.
"I've never been pestered so much on Twitter and even in clubs and on the street about who's playing Bestival this year so we thought we'd better start the proceedings," he said.
"Legendary brothers of rave Paul and Phil Hartnoll aka Orbital are the first act who have self-announced themselves today, and what a classic to kick off on."
He added: "As ever the theme of Bestival is a hotly-debated topic - this year it's Wildlife - so maybe you're thinking foxes, badgers or flamingos or go a bit more lateral and think of wild men and women, hedonists and crazy people? It's an open book as ever. More news very soon!"
The festival also features vintage cinema the Lost Picture Show with da Bank rescoring the 1933 King Kong.
Revellers can meditate at the Soul Park with support from the David Lynch Foundation, eat with the Young British Foodies, party at the Arcadia Mechanical Cabaret, drink at the Grand Palaec of Entertainment and more.
Earlybird tickets are available now and are priced at £170 for entry from Thursday, September 6 and £165 for entry from Friday, September 7.
Teen tickets (13-17) are priced at £110/£105 and those aged 12 and under get free entry but must obtain a ticket.
Watch Orbital perform the 'Doctor Who Theme' with special guest Matt Smith at Glastonbury 2010 below: