As a child, Karan Johar always dreamt of being famous. His father, Yash Johar was a top filmmaker, so Karan grew up amidst the company of Amit uncle and Jaya aunty, who were close friends of his parents. Like most star children, he too went for Hrithik and Abhishek's birthday parties where he met up with other kids, many of whom have grown up to become famous stars today. Kareena and Karisma Kapoor, Twinkle and Rinke Khanna, Aditya and Uday Chopra, Abhishek and Shweta Bachchan, Goldie and Shrishti Behl, Hrithik and Sunaina Roshan, Tusshar and Ektaa Kapoor were few of his childhood friends but they all drifted apart as childhood soon turned to adolescence.

When Karan was schooling at Green Lawns, he used to be a complete movie buff. However, having lived and studied in South Mumbai all along, he hardly had any filmi friends. He wasn't very proud when people came up to him and asked him if he was Yash Johar's son. At that time and in that side of the city, being associated with films wasn't something to be thrilled about. So he often denied any connection with the movies, insisting that his father was not a producer, but a businessman. But within, Karan was an ardent Hindi movie buff, who would rush home after school to catch his favourite movie on video. He had his own collection of the latest Hindi films and saw Yash Chopra's Silsila every single day. He loved trial shows and would often burst into tears when his parents refused to take him for preview screenings. As Karan grew up, he realized that his love for cinema kept growing too, and when he was studying at H R College, he got friendly with Aditya Chopra, Yash Chopra's son. One day, Aditya called up Karan, wanting to narrate his gem of a story idea he had.

That film was Dilwale Dulhania Le Jayenge. The next two months saw Karan working along with Aditya on the scripting of the film, till one day Adi asked him to assist him on the film. Karan, who had just finished his French course and was all set, to go get a degree in Mass Communications from Paris. But his passion for the movies made him change his mind and the rest is history. While working on 'Dilwale Dulhaniya Le Jayenge', during the Switzerland schedule of the film, one day Shah Rukh Khan suggested to Karan to direct his own film. That was how his debut Kuch Kuch Hota Hai was born. The film ended up, as one of the biggest blockbusters of all time and Karan was a superstar director before he realized it. For a teenager who grew up on the works of Raj Kapoor and Yash Chopra, he was now a successful filmmaker himself.

After that, Karan took a break for a year as good friend Adi was making Mohabbatein. After 'Mohabbatein' released, Karan announced his next venture, Kabhi Khushi Kabhie Gham, which starred Amitabh Bachchan, Jaya Bachchan, Shah Rukh Khan, Kajol, Hrithik Roshan and Kareena Kapoor. It turned out to become a huge box-office success in India and overseas.

His next few productions were Kal Ho Naa Ho (2003) and Kaal (2005), which were directed by Nikhil Advani and Soham Shah respectively. His directorial next, Kabhi Alvida Naa Kehna (2006), starring Shah Rukh Khan, Abhishek Bachchan, Preity Zinta and Rani Mukerji, was based on the theme of adultery. It did great business at the box-office, despite receiving backlash from some quarters for its subject.

In the meanwhile, he also started hosting a television show, 'Koffee With Karan', which had three seasons in 2004, 2007 and 2010. He even produced films such as Kurbaan, Wake Up Sid, I Hate Luv Storys, Dostana, Agneepath etc.

His fourth film, My Name Is Khan (2010), starring Shah Rukh Khan and Kajol, was based on the repercussions of 9/11. The film got critical acclaim and notched up good box-office numbers as well.

His latest solo directorial venture was Student Of The Year (2012), which starred three rank newcomers - Alia Bhatt, Sidharth Malhotra and Varun Dhawan. The film did very well at the box-office. In 2013, his film, Bombay Talkies released. This four-part film was made to celebrate 100 years of Indian cinema. Besides Karan, the other three directors working on the film were Anurag Kashyap, Zoya Akhtar and Dibakar Banerjee. Karan's segment starred Rani Mukerji, Randeep Hooda and Saqib Saleem. 

His upcoming productions include Yeh Jawaani Hai Deewani, Gori Tere Pyaar Mein and Hasee Toh Phasee.