One Direction will headline this year's iHeartRadio Music Festival.

The boyband will be joined by acts including Taylor Swift, Ariana Grande, Ed Sheeran, Iggy Azalea, and Lorde, on the main stage at the annual event which will take place over two nights at the MGM Grand Hotel & Casino in Las Vegas on September 19 and 20.

Coldplay, Usher, Nicki Minaj, Motley Crue, Zac Brown Band, Paramore, Train, Eric Church, Calvin Harris, Bastille, and Steve Aoki have also been confirmed to play at the star-studded gathering.

Ryan Seacrest will once again return as host for the music festival's fourth year in Las Vegas.

Tom Poleman, president of Clear Channel's national programming platforms, told Billboard: ''We want to continue to deliver the goods for artists and help their development, and to see more great music to keep the radio industry healthy.''

He added: ''It's great to have the diversity of genres this year, too. We have Motley Crue, which is obviously very different from Train, Eric Church, or Ariana Grande, but that's what makes it so special.

''You'll often have people on the side of the stage watching other bands. It's not unthinkable to see someone like Coldplay watching Zac Brown or One Direction because they're already on-set and they never get to see them play themselves.''