Usher will play the opening night, Norah Jones will return to headline on September 10, One Direction are performing on September 20 and Jack White is set to make his iTunes Festival debut on September 8.
More headliners will be announced soon.
Norah Jones said: "Can't wait to return to London for the iTunes Festival and play in a venue with such deep history.
"It's great to be on a bill with an amazing range of artists and to be on the same stage on which The Stones, Bowie, The Ramones, The Clash and so many others played."
Tickets are free for competition winners only. For more information visit: www.itunesfestival.com.