Karan was born in Wimbledon, London in 1984 to Sri Lankan Tamil parents who had emigrated to Britain from Zambia two years before she was born. She was brought up in Wimbledon and attended Wimbledon High School.
Karan went on to study at St Catherine's College, Oxford and while there began acting in amateur plays including Sunday Morning at the Centre of the World at the Burton Taylor Theatre for which she received rave reviews and was also singled out for her performance in When We Are Married at the Old Fire Station theatre. During her time at Oxford, Karan wrote, directed, produced, and acted in a short film, By Myself, which came in second place in the 2002 Shoestring Shorts Competition.
She carried the 2008 Olympic Torch during its time in London.
