The Duke of Mantua has his eye on a lovely young woman he has seen in church. Although he does not know who she is, he is determined that she will be his. In the meanwhile, the libertine Duke is engaged in an affair with Countess Ceprano, whom he encounters at a festive ball in his palace. As Count Ceprano furiously watches the Duke leaving the hall with the Countess, the Duke’s court jester, Rigoletto, cruelly mocks his ill-concealed anger.
Marullo, a courtier, excitedly reports the unlikely news that the deformed jester apparently is keeping a mistress. Count Ceprano and the other members of the court, all of whom have been the butt of Rigoletto’s humor at one time or other, decide to take revenge against the jester.
The aged Count Monterone enters in a fury to accuse the Duke of seducing his daughter. Rigoletto relentlessly insults Monterone, who curses the jester for mocking a father’s grief. Rigoletto is shocked to find himself suddenly filled with dread.
Rigoletto has raised his daughter Gilda alone after her mother’s death, and has kept her in the secret care of a nurse, far away from the debauchery of the Duke’s court. As he walks home, Rigoletto is still greatly disturbed by Monterone’s curse. He encounters Sparafucile, a hired assassin, who offers his services. Rigoletto sends Sparafucile on his way after learning where he might find him later.
The Duke arrives in disguise at Gilda’s house, and she recognizes him as the young man who followed her home from church. The Duke pretends to be a poor student named Gualtier Maldè, and they exchange words of love. When he has gone, Gilda is left alone. A group of courtiers (assuming that Gilda is Rigoletto’s mistress) trick Rigoletto into assisting with his own daughter’s kidnapping.
The Duke, having returned to Rigoletto’s house to see Gilda, is distraught to have found the place deserted. Back in the palace, he genuinely mourns the loss of a woman whose love might have inspired him to lead a virtuous life. The courtiers return and report the kidnapping of Rigoletto’s “mistress,” whom they have brought to the palace. Relieved, the Duke hurries to the room where Gilda is concealed. Rigoletto enters and tries to find his daughter’s whereabouts. He denounces the courtiers for their cruelty. Gilda rushes into her father’s arms and, ashamed, confesses liaison with the Duke. Rigoletto vows revenge, despite Gilda’s pleas on the Duke’s behalf.
Rigoletto disguises Gilda (who still loves the Duke) in men’s clothing and plans their escape from the corruption of Mantua. He also hires Sparafucile to kill the Duke. Sparafucile’s sister Maddalena assists in the scheme by luring the Duke to her house. Maddalena feels sorry for her handsome victim, and persuades Sparafucile to let him live; instead, they will kill their next visitor. Overhearing this, Gilda decides that she will sacrifice her own life for the Duke’s. When Rigoletto returns to claim the Duke’s body, the jester is shocked to discover that it is his own daughter who has been murdered.