The actor can currently be seen in romance Cocktail opposite Deepika Padukone.
Producer Bhushan Kumar told The Times of India: "After Ready, my next film, an untitled one, will be directed by Milan Luthria.
"As Ready did 100 crore-plus business, we will continue to dabble in film production in a big way. We do not wish to make multiple films but would rather do a few good projects... no run-of-the-mill stuff for us.
"Milan's film for us is a family entertainer, with Saif as a superhero for the first time," Kumar continued. "I am excited. We are very happy to have him on board. We wanted someone who could make people laugh, and Saif is perfect.
"The film will have action, adventure, suspense, comedy and music - in short, it's a complete masala film! We should start filming in 2013.
"Saif and I have been talking about a film together for a long time. This time it had to happen, I guess. I had a character that fit him to [a] T. Most importantly, he just said 'yes' over the phone!"
Kumar added: "It was an instinctive move from both of us and I was thrilled that an actor of his stature has so much faith in me! It was definitely a magic moment. He was in Istanbul and I was in Prague - it just happened so fast."
Khan said in March of this year that the sequel to his hit film Agent Vinod could be produced in 3D.
He has also hinted that the feature could become part of a James Bond-style franchise.
Watch a trailer for Agent Vinod below: