Rihanna will perform her new single for the first time, Sam Smith will deliver his soulful vocals, and Taylor Swift will be in the audience dancing along in her typical awards show form.
The iHeartRadio Music Awards will debut its second annual show Sunday night from the Shrine Auditorium in Los Angeles.
Justin Timberlake will accept the 2015 iHeartRadio Innovator Award for his accomplishments as an entertainer.
Rihanna will sing "B---- Better Have My Money," released days ago.
Other performers include Madonna, Iggy Azalea, Florida Georgia Line, Jason Aldean and Meghan Trainor.
Jamie Foxx, who will host the show airing live on NBC, will also take the stage to perform a new song.
Swift, who is nominated for four awards including artist of the year, won't perform, but she is part of the line-up of attendees, who include Ludacris, Ryan Seacrest, Gina Rodriguez and Jeremy Piven. Guests at the iHeartRadio Music Awards will sit at traditional tables — in the vein of the Golden Globes — instead of typical awards show seats.
Smith and Azalea are the top nominees with five apiece. They, along with Ariana Grande and Luke Bryan, will compete with Swift for artist of the year.
Song of the year nominees include Trainor's "All About That Bass," John Legend's "All of Me," Pharrell's "Happy," Swift's "Shake It Off" and Smith's "Stay With Me," the only song in the group to not hit No. 1 on the Billboard Hot 100 chart.
Kelly Clarkson, Snoop Dogg, Jason Derulo, Jennifer Hudson, Alesso and Nate Ruess of fun. will perform at the three-hour event, which will also air live on iHeartMedia's radio stations.