iTunes Festival 2014 line-up: Pharrell, Calvin Harris and 5 Seconds of Summer among acts

Over 60 artists will take to the stage at London's Roundhouse in September

Pharrell Williams, here performing at the Wireless Festival in London's Finsbury Park (PA)

Pharrell Williams, Kylie Minogue and Calvin Harris are among the acts lined-up for this year’s iTunes Festival at London’s legendary Roundhouse.

Thirty nights of live music are scheduled for September, with rising star Sam Smith, Australian boyband 5 Seconds of Summer, DJ David Guetta and newcomer Kiesza also booked to perform.

"Even though we're from Australia, we're well aware what an iconic venue the Roundhouse is...and we've played enough square ones!" joked 5 Seconds of Summer.

The popular event, returning for an eighth year, will see more than 60 artists take to the stage. Fans can win free tickets by entering the official ballot, which can be accessed via the iTunes store.

Other acts set to play the 2014 extravaganza include Blondie, Chrissie Hynde, Robert Plant, Beck, Jungle, Maroon 5 and recent Glastonbury headliners Kasabian.

"We've been roaring around the world this summer from Morocco to the Arctic Circle," said Plant. "The band is on fire. It's now time to shake it on down in NW1."

Since the iTunes Festival began, over 430 acts have performed in front of some 430,000 fans. Past headliners have included Justin Timberlake, Adele, Katy Perry, Lady Gaga and Elton John.

In March, the festival expanded to US event SXSW in Austin, where Apple hosted concerts by Soundgarden, Pitbull, Coldplay and more.

Those not lucky enough to bag London tickets can still watch the forthcoming gigs, as live streams will be available through the iTunes store in more than 100 countries.