The 49-year-old "Happy New Year" actor will be seen playing the role of both a superstar and his fan in the movie produced by Yash Raj Films.
"Whatever anyone might say... The honest truth is that whenever I see FAN the film, I become arrogant. Thanks Maneesh and team for finding me again," Shahrukh wrote.
The teaser of Sharma's project, who lived with the idea for eight years was released in July.
The clip had King Khan doing his signature arms open pose and a fan impersonating the superstar during a performance in front of his home crowd.