A splendid hall in the ducal palace.
During a fête at the palace, the Duke of Mantua confides to one of his courtiers his intention to crown the amorous adventure he has started with a mysterious girl (Introduction: «Della mia bella incognita borghese»). He concludes by declaring that he is equally attracted by every beautiful woman, and will never be faithful to any («Questa o quella per me pari sono»).
The Duke now brazenly courts the Countess Ceprano, much to the fury of her husband the Count, who is cynically ridiculed by Rigoletto, the hunchback court jester protected by the Duke. Count Ceprano is determined to get his revenge on the jester, and finds solidarity among the other courtiers whom he invites to his house that same evening.
At the height of the festivities, Count Monterone enters and upbraids the Duke for having dishonoured his daughter. On hearing more jibes from the jester, Monterone curses him for making fun of a father’s sorrow. Rigoletto is inwardly struck by these words.
The deserted end of a blind alley.
It is night. Rigoletto, still shaken by the curse that has been laid upon him, bumps into Sparafucile, the bravo, who offers him his services (Duet: «Quel vecchio maledivami!»). Alone now, Rigoletto reflects on his condition as a buffoon, forced to serve laughter to an evil master and to be hated by his courtiers (Scena: «Pari siamo!...»).
The door of a little house now opens and out of it comes Gilda, the jester’s affectionate daughter had by a woman once loved who later died (Duet: «Deh non parlare al misero»). The jester hides his identity from her and keeps her concealed from the world, forbidding her to go out or to meet anybody.
Rigoletto takes his leave, after reminding Giovanna to keep watch over his daughter. To this woman Gilda confides her remorse at having met a young man and not having told her father (Scena: «Giovanna?... ho dei rimorsi...»).
Suddenly the Duke of Mantua appears, having made his way into the courtyard by stealth, and tells the girl that he is a poor student named Gualtier Maldè. Gilda is visibly stirred by his declaration of love (Duet: «È il sol dell’anima»). When the Duke has gone, she ponders rapturously over his beloved name (Aria: «Caro nome»).
In the meantime the courtiers have arrived to implement their plan. They abduct Gilda, whom they believe to be the jester’s lover, and even manage to involve Rigoletto himself in the action, by making him believe that the abducted woman is the Countess Ceprano (First finale). Too late, the jester realises he has been tricked.
A drawing room in the ducal palace.
The Duke is uneasy because on the previous night, after returning to the house in which he had met Gilda, he found the door open and nobody at home (Scena and aria: «Parmi veder le lagrime»). The courtiers tell him they have abducted Rigoletto’s lover.
The Duke understands that she is in fact Gilda and hurries to meet her. Rigoletto now enters, feigning indifference (Scena: «Povero Rigoletto!»). When he guesses that the Duke is with his daughter, he is tempted to rush to her aid, but his path is barred. He then reveals that the girl is his own daughter, inveighs against the courtiers, begs mercy and weeps, but in vain (Aria: «Cortigiani, vil razza dannata»).
Suddenly Gilda emerges from behind the closed door and wishes to speak to her father. He sends everybody out (Scena: «Mio padre!»). The girl confesses to him that she fell in love with a young man she had seen in church every Sunday, and that she had met him the day before and been abducted (Cantabile: «Tutte le feste al tempio»).
Rigoletto consoles her. Meanwhile Monterone passes by, on his way to prison. He glances at the portrait of the Duke and recognizes that his curse has not come true. But Rigoletto assures him, despite his daughter’s anguish, that he personally will vindicate the offence (Cabaletta: «Sì, vendetta, tremenda vendetta»).
A desolate spot on the banks of the river Mincio.
Rigoletto has brought Gilda to a house, the ground floor of which serves as an inn, so that by spying on its interior she will understand the true identity of the man she loves (Scena: «E l’ami? / Sempre»). The Duke arrives, and orders Sparafucile to serve him food and drink, while he praises the fickleness of women (Song: «La donna è mobile»).
From upstairs descends Maddalena, Sparafucile’s sister, in gypsy apparel. The Duke flirts with her, while from the outside Gilda sees all and despairs at his betrayal (Quartet: «Un dì, se ben rammentomi»).
Rigoletto orders Gilda to leave at once for Verona, where he will join her the next day. He then makes a rapid arrangement with Sparafucile to murder the Duke (Scena: «Venti scudi hai tu detto?»).
The Duke goes up to sleep in the loft. Maddalena, alone now with her brother, tries to convince him to spare the life of the young man, whose charm has had its effects on her too, by killing Rigoletto instead. Sparafucile refuses, but agrees to slay the first person who happens to arrive instead of the Duke (Trio: «È amabile invero cotal giovinotto»).
Gilda, who has heard all, decides to sacrifice herself. She knocks on the door and is stabbed by the ruffian (Storm). On the stroke of midnight Rigoletto sees Sparafucile coming out of the inn to deliver the sack containing the victim’s body (Scena: «Della vendetta alfin giunge l’istante!»). The jester is about to throw the sack into the river, when from the house he hears the Duke’s voice singing.
He tears open the sack and, to his horror, finds in it the body of his dying daughter, who with her last breath confesses what happened (Duet: «V’ho ingannato! colpevole fui!»). Rigoletto, remembering the curse, collapses beside his daughter’s dead body.