The music for Rockstar is scored by A. R. Rahman and the lyrics of Rockstar songs are penned by "Irshad Kamil". The audio rights has been bought by T-Series. Music will under t-Series label. 

Mohit Chauhan is the voice of Ranbir Kapoor (The Rockstar) in this film Rockstar. In promos we can see it's Mohit Chauhan's voice suits to Ranbir's personality. Ranbir acted brilliantly as the promos and songs are concerned.

 Mohit Chauhan sang most of the songs. Imtiaz did good that he chose only one singer for Ranbir's character. many times in Bollywood we see one actor acts/lip-sync for various singers in same movie.