Chicago is set in the year 1924, a time when Roxie Hart witness the star Velma Kelly makes a performance. Roxie Hart enters a relationship with Fred Casely, who told her that he knows that manager of the theater where Velma performs. Velma, on the other hand gets arrested for murdering her husband and his mistress who turns out to be her sister. Eventually, Fred confesses that he does not know any manager who can help Roxie so Roxie shoots him dead. She convinces her husband Amos to take responsibility when she tells him that Fred was a burglar. However, during the investigation some evidence point out that Roxie had a connection with Fred. Because of this, Amos tells the truth to the police and Roxie gets arrested for Fred’s death.
At Cook County Jail, Roxie meets Velma but she refuses to be friends with her. With the advice of the prison matron, Roxie convinces Velma’s attorney to help her in making a good appearance with the public. Her reinvented story catches the attention of the people and Velma loses the spot under the lime light. Velma tries to persuade Roxie to join her but Roxie rebuffs her just like what she did before.
When a wealthy woman gets the public’s attention when she gets arrested for the murder of his husband and his two lovers, Roxie makes a move right away by telling everyone that she’s pregnant. Roxie is advised by her lawyer to tell people that the child is Fred’s. Thinking that she can handle everything on her own, Roxie ditches her lawyer but rehires him again when a woman from the Murderer’s Row gets hanged.
During the trial, Roxie’s lawyer does everything to make her case sensational to the public. Just as Roxie seems to be gaining favors, Velma offers Roxie’s diary which purportedly contains incriminating entries that she uses in exchange for her amnesty. Velma walks out free and Roxie is acquitted as well. It is revealed that the lawyer manipulated the entries on the diary so he can set both Velma and Roxie free. Though Roxie’s husband still loves her, she ditches him and confesses that she’s not pregnant at all.
Velma and Roxie try their luck in vaudeville separately but both do not achieve success. When Velma offers partnering up with Roxie again, the latter hesitantly agrees. During their performance together, they audience and even the press love their act very much. The movie ends with the audience making a standing ovation for Roxie and Velma.