Mithoon first started out in the Mahesh Bhatt camp adapting popular Pakistani Pop Songs into Hindi movies most notably Woh Lamhe from the movie Zeher sung by Atif Aslam. He then did the same thing for Mahesh Bhatt for the film Kalyug. The song was Aadat also sung by Atif Aslam. Since then he has moved on to composing his own music as a guest composer in movies like Bas Ek Pal and Anwar. Although th movies did not do well, the music was well received and his work was appreciated.In 2007 Mithoon replaced Himesh Reshammiya for composing the soundtrack for the movie Aggar. Mithoon also sang in Aggar, dispaying his powerful voice. Earlier his full movie album The Train : Some Lines Should Never Be Crossed marked his very first full album composition for a Hindi movie.