At 41, the multi-talented persona plans to work on creating a family for himself.
In an interview with The Times of India, Johar said,"Now I am 41 and there is an empty space in my life that I can't plan for, but what I can plan is a family and I am working on it."
Johar entered the film industry as an actor in Aditya Chopra's 'Dilwale Dulhania Le Jayenge' in 1995.
He later made his directorial debut with the highly successful romantic film, 'Kuch Kuch Hota Hai' (1998) which won him a Filmfare Award For Best Director and Filmfare Best Screenplay Award.
His subsequent directorial efforts were the family drama, 'Kabhi Khushi Kabhie Gham' (2001) and the romantic drama, 'Kabhi Alvida Naa Kehna' (2006), a movie which dealt with the theme of adultery.
Both films were major financial successes in India and abroad.
Johar thus traversed a long way to establish himself as one of the most successful filmmakers in Bollywood.
His fourth film, 'My Name Is Khan' (2010) was met with positive reviews and grossed 2 billion (US$37 million) worldwide. It earned him his second Best Director award at the Filmfare ceremony.
He is the head of the production company Dharma Productions, which has delivered some of Bollywood's highest grossing films in India and abroad.
Even at 41, Johar is expected to meet with success with his upcoming production venture "Yeh Jawani Hai Deewani" starring Ranbir Kapoor and Deepika Padukone.
Besides films, Johar has established himself as a popular host of the celebrity-based chat show 'Koffee with Karan', in which he interviews renowned celebrities from Bollywood and India's glamour world.
At present, he is all set to join Madhuri Dixit and Remo D'Souza as the judge of the upcoming season of celebrity dance show 'Jhalak Dikhhla Jaa'
Celebrities took it to Twitter to wish Johar on his birthday.
Fashion Designer Manish Malhotra tweeted:" My dearest friends birthday @kjohar25 :-)"
Filmmaker Nikhil Advani tweeted:"Happy bday @kjohar25. Today is significant for the many you have touched, nurtured, mentored and most importantly entertained. Cheers!!!"
Actress Neha Dhupia tweeted:"Happy birthday @kjohar25... Have an absolutely fantastic year !"
Filmmaker Sujoy Ghosh tweeted:"as the bengali papers read.. it korno johor's jonmodin (birthday).. so happy happy @kjohar25.. make lots of films for us."