He joined Illaiyaraja's troupe as a keyboard player in order to earn for his family's upkeep. He also learnt to play the guitar. Thus Rahman formally entered the world of music. He also began to play the keyboard for programmes on television.He also played on the orchestra of M.S.Vishwanathan, Raj-Koti and Ramesh Naidu and accompanied Zakir Hussain and Kunnakudi Vaidyanathan on world tours. He also appeared playing the keyboard on a few popular music shows on televison like 'Wonder Balloon' (KaNmaNi PoongA/Wonder Balloon -Madras DD produced Thamizh/English serial for kids) on the Madras Doordarshan channel. He also supposedly composed a few short pieces of music in Ilaiyaraja's films, a notable one being the theme music in K.Balachander's 'Punnagai Mannan(1986)' Starring Delhi Ganesh ,Kamal Hassan,Rekha,Revathi and Srvidya.

Dileep thus firmly established himself this way and worked for nearly 8 to 9 years with various music directors. He also worked as an arranger for Illaiyaraja, M.S.Vishwanathan, Ouseappachan and Raj-Koti. He has this to say of his stint with Illaiyaraja "Until then I thought you had to drink or take dope to be a good artist. But Ilayaraja was making such beautiful music and leading a pure life!'' " I was under the impression that if its music, whoever it is, they must have some bad habit. When I saw them with drinks and drugs I thought 'Oh! they are music people. They have to take drinks, smoke and cocaine to get their inspiration'. The man who changed these impressions altogether was only Ilayaraja. He proved that he can make good music without any bad habits! Even now he is an inspiration for me being so religious today."