The three-day dance music event will return to its home at Daresbury in Cheshire across the weekend August 22 to 24, reported Digital Spy.
Avicii, 24, will head up the South Stage on August 23, while deadmau5 will top the North Stage.
Harris will headline the North Stage on August 24, while Tiesto will head up the South Stage.
Afrojack, Martin Garrix, Steve Aoki, Armin Van Buuren, Showtek, Steve Angello, Hardwell, Eric Prydz, Annie Mac, Skream, Pete Tong, Fatboy Slim, Nervo and Alesso have also been added to the list.