The movie is based on the true story of the gang war that lasted between two groups in the 80s and 90s in Ghaziabad, India. In the town of Ghaziabad, Brahmapal Choudhary (Paresh Rawal) is a corrupt chairman, and has connections with the gangster Fauji (Arshad Warsi), who is willing to do anything to make a quick buck. When Jagmal refuses to pay up to 2 million for Fauji's sisters wedding, Fauji breaks their ties and leaves him. At the same time, Brahmapal befriends a polite teacher named Satbir (Vivek Oberoi) who also happens to be in a relationship with Jagmal's daughter Suman (Charmy Kaur).

Thinking that Jagmal has replaced him with Satbir, Fauji becomes furious and joins forces with Rashid (Ravi Kishan), a politician and Brahampal's enemy. Rashid deliberately turns Fauji against Satbir, making him think that he wants him dead. When Fauji tries to attack Satbir, an elderly village spokesman is shot, leading Satbir to fight back against him. But before Satbir is able to do anything about it, Satbir's older brother Karamvir (Chandrachur Singh) is kidnapped, and soon killed by Fauji. Seeking revenge, Satbir turns to the crime world to finish off his brother's murderer. With riots taking place all over, the police department shifts a crazy, tough, feared and solid officer, Thakur Pritam Singh (Sanjay Dutt) to enter the city bring a stop to this gang-war. However, Pritam Singh ends up making it all worse.

Pritam Singh initially visits Fauji and Rashid and later on, invites Satbir to the Police Station. Having gauged their attitudes, Pritam Singh decides to side with Satbir in the war against Fauji and Rashid. With elections approaching, both parties eventually decide to contest with Rashid and Satbir's brother contesting. Rashid wins the election seeing which Fauji goes on a killing spree beginning his attack starting from Satbir's house and accidentally ends up killing Satbir's now wife Suman. Enraged at this act of Fauji, Satbir's brother kidnaps his girlfriend – an act that is looked down upon by Satbir. Before she could be returned safely, Fauji invades the place and kills Satbir's brother prompting a furious Satbir to go on a revenge spree.

In the meanwhile, a tape is discovered which not only reveals that Rashid and Faqeera have secretly made a deal with Pritam Singh to murder Fauji, thereby betraying him, but also shows Faqeera confessing to having ordered the attack on Fauji's house at the start of the movie which is what triggered the whole gang-war in the first place. Furious at this betrayal, Fauji kills Faqeera and then heads out to kill Rashid. Pritam Singh also joins in, apparently fulfilling his promise to kill Fauji for Rashid but ends up killing Rashid instead. This results in an action-packed finale that sees Satbir killing Fauji and being arrested by Pritam Singh. His fate then is left unknown.

• Sanjay Dutt as Police Inspector Thakur Pritam Singh
• Arshad Warsi as Mahendra Fauji
• Vivek Oberoi as Satbeer
• Ashutosh Kaushik as Pandit
• Ravi Kishan as Rashid Ali
• Charmy Kaur as Suman, Chairman Brahmapal's daughter
• Sunil Grover as Faqeera
• Paresh Rawal as Brahmapal Choudhary (Chairman)
• Minissha Lamba as Kavita, Fauji's girlfriend
• Chandrachur Singh as Karambeer, Satbeer's elder brother
• Ashutosh Rana as Sangram Singh
• Divya Dutta as Mahenderi^[3]
• Geeta Basra in "Baap ka Maal" Item song (special appearance) ^[4]
• Shriya Saran in "Chhamia No 1 " Item song (special appearance) ^[5]
• Zarina Wahab as Satbeer's mother
• Eijaz Khan as Ombeer Singh
• Parth Sharma as Robin Singh
• Geeta Khanna as Rashid's mother

The soundtrack of Zila Ghaziabad is composed by Amjad Nadeem, with Bappa Lahiri, son of famous music composer Bappi Lahiri composing "Tu Hain Rab Mera" The album contains five tracks. Lyrics by Shabbir Ahmed.