A party in the palace of the Duke of Mantua. The Duke boasts to his friend Borsa that he is about to complete the conquest of a beautiful young woman he has seen at church. He then dances with the lovely Countess Ceprano, flatters her, and escorts her from the room. The Duke’s odd-looking jester, Rigoletto, mocks the Countess’s jealous husband. The courtiers, all of whom hate Rigoletto, are astonished to hear a rumor that this ugly, hateful man keeps a mistress. Rigoletto suggests the Duke banish, execute, or imprison Count Ceprano. The Count swears vengeance on Rigoletto. Suddenly Monterone, an elderly nobleman, enters and accuses the Duke of having seduced his daughter. Rigoletto ridicules him, whereupon Monterone curses both Duke and jester.
That evening, Rigoletto’s home. The sound of Monterone’s curse ringing in his ears, Rigoletto is returning home when Sparafucile, an assassin, offers his services. Rigoletto politely declines, then muses on what he has in common with the murderer. As he enters his home, a young woman rushes into his arms: his ‘mistress’ turns out to be his daughter, Gilda. She questions Rigoletto about his name, his occupation, and her mother, but her father avoids answering her questions. He charges Giovanna, Gilda’s servant, never to admit anyone into the house. As Rigoletto leaves, the Duke slips into the garden.
Gilda tells Giovanna of a handsome stranger whom she sees at church. Suddenly the Duke, her unknown admirer, steps forward and declares his love, saying he is a penniless student. They sing a rapturous love duet, “È il sol dell’anima;” but then, hearing footsteps, Gilda begs “Gualtier Maldé” to leave.
The footsteps turn out to be the Duke’s courtiers, who are plotting to kidnap Rigoletto’s “mistress.” When Rigoletto, returning home, stumbles into them in the dark, they tell him they’re kidnapping Ceprano’s wife, and he eagerly offers to help. While he holds the ladder, they carry Gilda off. He recognizes her voice as she calls for help—too late. Realizing what has happened, the jester recognizes the work of Monterone’s curse.
The next morning; The Duke’s Palace. The Duke fumes over the news of Gilda’s kidnapping; he wonders whether she might be the only woman he could love faithfully (aria: “Parmi veder le lagrime”). His courtiers enter, hoping to cheer him up with the humorous story of the prank they’ve played on Rigoletto. Realizing they’ve brought the young lady in question to his palace, the Duke rushes off to complete his seduction of Gilda.
Rigoletto confronts the courtiers, and when they block him from entering the room where Gilda is with the Duke, he begins the aria “Cortigiani” with an explosion of fury and frustration. That gets him nowhere, so he falls to his knees, cringing and whimpering, begging them for mercy. Even when he recovers his dignity and asks them simply to give an old man back his daughter, they refuse him.
Gilda appears and Rigoletto orders the others to leave. Gilda tells her father of the Duke’s courtship and her capture. Rigoletto vows he will wreak the vengeance of Monterone’s curse on the Duke, but Gilda begs Rigoletto to pardon the man she loves (duet: “Si, vendetta”).
Several weeks later, evening; a dilapidated inn on a river-bank. Rigoletto and Gilda are outside the seedy tavern where Sparafucile lives with his sister Maddalena. The Duke enters, sings the aria “La donna è mobile,” and calls for Maddalena. Rigoletto forces Gilda, who still believes the Duke loves her, to watch the Duke seduce Maddalena.
Rigoletto tells Gilda to disguise herself as a man and travel to Verona, where he will join her the next day. Sparafucile comes out of the inn and collects half his fee from Rigoletto for the delivery of the Duke’s body at midnight. Rigoletto leaves.
Gilda appears outside the inn, dressed as a man. Inside, Maddalena, who has fallen for the Duke, begs her brother not to kill him. She convinces him to kill, instead, the next stranger who comes to their door. Gilda overhears their conversation. Even though the Duke has betrayed her, she is determined to sacrifice her own life to save his. She knocks on the door. Sparafucile stabs her.
Rigoletto returns to the inn, and Sparafucile drags out the sack containing the victim. Rigoletto hears the voice of the supposedly murdered Duke in the distance, opens the sack, and finds his beloved daughter. She tells Rigoletto that she wanted to die to spare the Duke and asks for Rigoletto’s forgiveness before she dies.