Billu Barber is story that shows how Billu’s (Irrfan Khan) life is changed when a film unit arrives at his village for shooting a movie. To Billu’s surprise, the star of the movie is none other than Sahil Khan (Shah Rukh Khan) who was Billu’s old school friend. Instantly, Billu becomes prominent man in the village and attains fame and respect. Villagers urge him to make acquaintance with the superstar, but Billu is intimidated by his friend’s superstar status. He thinks that Sahil would never acknowledge his friendship with a barber. Billu strives to meet the star but is unsuccessful. Finally, he fails after lots of struggle.
People suspect that Billu is fibbing in order to gain fame and start offending him. Billu’s family and children become apprehensive about his claim. In the end, for an invited school function, the star reveals his past. He tells the audience that in his school days he had a friend who always stood by him in his hardships. He tells how much the friend helped him by providing food when he was hungry, provided clothes when he did not having any. He tells that the friend gave him the money to join acting by selling his ancestral ear ring and that friend happens to be Billu. At that time the people recognize about Billu and the movie happily ends.