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Before starting his television acting career, Karan did many modeling assignments, ramp shows, advertisements and even hosted a radio show. Later, he entered the Gladrags Mega Model Manhunt Contest in 2004 and ended up winning the award for the Most Popular Model. Through a nationwide talent hunt contest he, along with five others, got selected to play leads in an MTV show Kitni Mast Hai Zindagi, followed by Princess Dollie Aur Uska Magic Bag. He was also seen in Kasautii Zindagii Kay in a negative role. Subsequently, he acted in Solhah Singaarr on Sahara One, as well as some short stints on C.I.D. and Parrivaar. Karan rose to fame through the role of Dr. Armaan Mallik in Dill Mill Gaye, which became widely popular and gained him a massive fan base. Along with Dill Mill Gayye, he anchored the STAR One reality television show Zara Nachke Dikha throughout its first season. He was the second runner-up in the dance reality show Jhalak Dikhhla Jaa in Season 3.
Initially, it was the role of the main lead opposite character of Meera played by Akangsha Rawat. But, later the story changed as Meera got married. His character re-entered the show in mid 2007 again for a little while and then exited in August, 2007.