The Jamie Foxx-hosted gala will air on NBC from the hrine Auditorium in Los Angeles on March 29, reported Digital Spy.
A new NBC promo for the iHeartRadio Music Awards also confirmed that Academy Award winner John Legend will appear.
Previously-announced acts include Taylor Swift, Madonna, Rihanna, Sam Smith and Florida Georgia Line.
Justin Timberlake will also be on hand to collect the 2015 iHeartRadio Innovator Award.
The coveted Artist of the Year category pits Iggy Azalea against Luke Bryan, Sam Smith and Ariana Grande. Azalea and Smith are also up in the Best New Artist category along with Bastille, Meghan Trainor and Cole Swindell.
The 2015 iHeartRadio Music Awards air on Sunday, March 29.