Small-time crook, Champak Chaudhary alias 'Champ' (Arshad Warsi) forges passports, photographs, and deeds in Thailand. He is arrested by the police, tried and sentenced to six months in jail. This is where he meets a supposedly mute and deaf inmate, Raghu Sharma (Raghuvir Yadav), serving a life sentence for stealing diamonds. Champ finds out that Raghu is not deaf nor mute and offers him a share if he springs him out of prison; Champ agrees. As soon as Champ's term is over, he gets discharged and prepares forged release documents for Raghu and gets him 'legally' out of jail.

The two then hide in a house deep in the country, where Raghu is re-united with his daughter, Jia (Minissha Lamba). Champ arranges for two fake passports for him and Raghu and get them two new identities: While he is now Anthony Gonzales, Raghu and Jia get Muslim names. Things do not go exactly as planned as Raghu is killed. Champ and Jia decide to part ways. But when Jia tells Champ she knows where the diamonds are buried, they agree on a partnership. Jia takes him where her dad had buried them — right in the compound of a penitentiary! While Champ plans to break back into prison, an underworld Don, orders his Assassin Munnabhai (Sanjay Dutt) to get hold of Anthony Gonzales and kill him — as Anthony has evidence that may link him to the murder of a young woman. Champ, who is now officially known as Anthony, will now use all the resources available to stay alive and, if possible, get the diamonds from the prison compound.

• Sanjay Dutt as Master Madan
• Arshad Warsi as Champak "Champ" Choudhary
• Minissha Lamba as Jia
• Raghuvir Yadav as Raghuu
• Anusha Dhandekar as Rosa
• Gulshan Grover as Inspector Suraj Singh
• Ravi Baswani as Dr. Lashwani
• Himesh Reshammiya as himself - Special Appearance

Anthony Kaun Hai was shot in the whole of Bangkok and Krabi, Thailand. Actor Sanjay Dutt drove a Ferrari 360 in the film.