"An extremely special film to me...#5YearsOfMyNameIsKhan," Karan tweeted.
The movie brought one of Bollywood's hit pairs Shah Rukh and Kajol together.
The 'Badshah' of the silver screen Shah Rukh also walked down memory lane and thanked the people associated with the film.
"My Name is Khan.....the only film I hav done 'In & As'. Thanx Karan Kajol SEL Ravi Deepa Shibani & everyone. Noor e Khuda," he tweeted.
The film revolves around Rizwan Khan, a Muslim who suffers from a form of autism, and marries a Hindu girl and how their life changes after the 9/11 terrorist attack in the US.