The Duke of Mantua surveys his court to choose a woman with whom to pass the night and selects the Countess Ceprano. She is flattered but nervous; her husband is present. This leads to an impasse. Marullo enters with news for his fellow courtiers that Rigoletto, the jester, has a mistress in town. The Duke then discusses his dilemma with Rigoletto, who suggests the following alternatives for Ceprano: prison, exile, or beheading. Ceprano and the courtiers are outraged and swear vengeance on Rigoletto. Monterone, an old nobleman, comes to denounce the Duke and his dissolute court. With the Duke’s consent, Rigoletto mocks the old man and his dishonored daughter. Monterone curses both Rigoletto and the Duke for laughing at a father’s grief. Rigoletto suddenly fears for the safety of his own daughter, whom he has kept carefully hidden from the court.
Later that evening, Rigoletto is accosted by Sparafucile, who offers his services as a killer. Rigoletto spurns his offer and then reflects on their encounter. He sees Sparafucile as his alter ego: one kills with a sword, the other with words. Monterone’s curse continues to haunt him.
Rigoletto returns home and greets his daughter, Gilda, declaring that she means the world to him. She reciprocates his feelings but questions why he has kept her concealed. He fears the courtiers and warns the nurse to guard Gilda carefully. Hearing a noise in the street, he goes out to investigate. The Duke, disguised as a student, enters and is astonished to discover the girl he has seen in church is Rigoletto’s daughter. He and Gilda declare their love. Then, fearing Rigoletto’s return, he leaves. Left alone, Gilda rhapsodizes on the false name of the “student,” Gualtier Maldè, while outside the courtiers gather to kidnap the woman they believe to be Rigoletto’s mistress. To exact their revenge on the jester, they will present the girl to the Duke. Rigoletto returns to find the courtiers near his house, but they fool him into thinking they have come to abduct Countess Ceprano who lives next door. Too late, Rigoletto discovers the trick.