Karthik is a Chennai-based playback singer. With an introduction by singer, Srinivas, to his hero A.R. Rahman, Karthik started his career in 1999 as a backup/chorus singer. A.R. Rahman also gave Karthik his first break with the song "Nendukitten Nendukitten" ("Jodi", 1999). His first big hit though came in 2001 when he sang "Maddy" in "Minnale".

Over the years, he has sung in a number of languages other than Tamil, including Hindi, Telegu, Malayalam, Kannada and Bengali.

He fronts a 5-piece band with musicians like Rolan Bennet. The band plays improvised versions of his popular songs and has performed at various events including IPL’s T20 matches.

Karthik has several Filmfare awards and a State award under his belt.