He studied chemical engineering in Sri Venkateswara College of Engineering.
After earning his Bachelor's degree, Karthik along with his friend Sunil Vishnu quit their respective jobs and started the event management company "Evam", which today is a theatre company of renown. Karthik made his acting debut with Alaipayuthey (2000) portraying a small role as the female lead character's prospective suitor.
He was first tested for the role of R. Madhavan in the film but was rejected as he was too young with no acting experience at the time.[4] He went on to portray supporting roles notably in films like Yaaradi Nee Mohini (2008) and Poi Solla Porom (2008).
In November 2016, Karthik lamented getting typecast in particular roles, especially as the American mappillai, and announced his retirement from the film industryHowever, he returned with a role in Rocketry: The Nambi Effect (2022).
