In Chicago during the year 1924, the innocent and ambitious Roxie Hart (Renée Zellweger) embarks on a night out at a popular nightclub. There, she is captivated by the dazzling performance of the renowned singer Velma Kelly (Catherine Zeta-Jones), who delivers the show-stopping number "All That Jazz." Roxie hopes that her date, lover Fred Casely (Dominic West), will help her land a spot on the vaudeville stage. However, the night takes a dark turn when Velma is arrested for the shocking murders of her husband and sister, who she discovered together in bed.
In the aftermath, Fred reveals he lied in order to seduce Roxie, igniting a fit of rage that leads her to fatally shoot him three times. In a desperate attempt to evade the consequences, Roxie convinces her husband Amos (John C. Reilly) to take the blame, fabricating a story about a burglar's involvement. The plot thickens when it is discovered that the victim was indeed Fred Casely, prompting Amos to abandon his alibi, and Roxie finds herself incarcerated at Cook County Jail.
Upon her arrival, Roxie is placed on "Murderess' Row," overseen by the conniving Matron 'Mama' Morton (Queen Latifah), who is notorious for accepting bribes and providing her inmates with luxuries like cigarettes. Here, Roxie encounters Velma and learns about the other women imprisoned for their own heinous acts.
Determined to gain her freedom, Roxie seeks the help of esteemed lawyer Billy Flynn (Richard Gere), and convinces her husband to speak to him on her behalf. Together, they craft a media-friendly narrative that transforms Roxie into a sensational figure, capturing the hearts of Chicagoans and inciting jealousy in Velma. As Roxie revels in her newfound fame, Velma attempts to revive her own star power by persuading Roxie to join forces for a vaudeville act.
However, tensions rise as both women vie for the spotlight, with Roxie stealing the limelight by falsely claiming to be pregnant, only to later reveal the deception. Meanwhile, she must contend with the haunting reality of another inmate's execution, which fuels her desire for freedom. The subsequent trial becomes a media frenzy, bolstered by sensational reports from eager journalists. Despite the dramatic twists and Velma's attempt to incriminate Roxie with her diary, Billy's clever tactics help secure Roxie's acquittal, though her moment of glory is fleeting.
Faced with the stark reality that celebrity is transient, Roxie unveils the truth of her deception to Amos, possibly leading to the end of their marriage. With her dreams of stardom still alive, Roxie initially declines Velma's proposition to team up. However, as Velma points out, the world of show business thrives on rivalry. Ultimately, the two former adversaries decide to join forces, and their collaboration ignites their careers.
In the powerful finale, the two murderesses achieve the success they have long craved, celebrating their talents on stage to an applauding audience, including Mama and Billy. The film encapsulates the glamour and darkness of fame, leaving Roxie and Velma poised for a dazzling future in the spotlight.
