Rathnam made his acting debut with the horror film Naalai Manithan (1989) in which he played John, a Psychotic Killer.
He played the leader of the fictional LTF rebels in the Hindi-language film Madras Cafe (2013).
His character bore a close resemblance to the late LTTE leader Velupillai Prabhakaran.
[5] His other side is seen as a motivational trainer and has transformed lives of thousands of children under his academy "STONE TO DIAMOND".
His son Dheeraj Vishnu Rathnam is also an actor who made his debut with Arivazhagan's Aarathu Sinam (2016).