A room in Count Almaviva’s palace. Figaro, the Count’s adroit valet, is anxious to marry Suzanna, the Countess’ maid. Suzanna informs Figaro, however, that the Count himself is trying to seduce her. Not only is Figaro’s happiness threatened but the marriage itself as well, for Figaro had one day borrowed money off Marcellina, Doctor Bartolo’s housekeeper, and they agreed that he would marry her if he would not be able to repay the sum. The imbroglio is intensified by Cherubino, the page who is in love with all women, especially the Countess. He asks Suzanna to put in a word for him with the Count, who intends to send him away because of an alleged flirtation with the gardener’s daughter Barbarina. Cherubino is forced to hide behind an armchair due to an unexpected entry of the Count. The latter now tries to win Suzanna’s affection but is disturbed in his attempts by noises behind the door. It is now the Count’s turn to hastily withdraw behind the armchair. The unwelcome visitor turns out to be Don Basilio, the music teacher, who is always full of intrigues and gossip. Basilio’s words provoke the Count and he steps forward in anger. He becomes even more enraged when he discovers Cherubino and realizes that the boy has overheard his attempts to seduce Susanna. He chases Cherubino into the great hall where they are met by Figaro, who has assembled the entire household to sing the praises of their master who allegedly waived the right of the first night. The Count is forced to bless the marriage of Figaro and Susanna. Due to Figaro’s mischief, the Count seems to forgive everyone, even Cherubino, so he appoints him an officer and immediately sends him off to his regiment in Seville.
The Countess’ boudoir. Figaro and Suzanna have submitted a plan to the Countess, how best to cure the Count of his infidelities. A forged letter is to inform him of an alleged lover’s meeting of his wife, but instead of the lover he is to find none other than Cherubino dressed up as a girl. Cherubino is about to try on skirts and petty-coats when the Count knocks on the door. Cherubino takes flight into the Countess’ closet and Suzanna hides behind a curtain. The Count enters suspiciously and gives the Countess Figaro’s fake letter. A noise is heard from the bedroom, but the door is locked and the Countess refuses to hand over the key. The Count, furious, decides to break open the door and asks his wife to come with him to fetch the necessary tools. Meanwhile, Cherubino, with Suzanna’s help, escapes through a window and she takes his place. When the Count and Countess return, both are astonished when Susanna emerges from the room. All seems well until the gardener, Antonio, appears, complaining that a man has jumped from the window, trampling his flowers. Figaro, who has rushed in to announce that everything is ready for the wedding, improvises quickly, feigning a limp and pretending that it was he who jumped. At that moment Bartolo, Marcellina, and Basilio arrive, putting their case to the Count and waving the contract that obliges Figaro to marry Marcellina. Delighted, the Count declares that Figaro must honour his agreement and that his wedding to Susanna will be postponed.
Legal proceedings against Figaro because of his promise given to Marcellina are under way. To save Figaro from trouble, Susanna leads the Count on with promises of a rendezvous that night. He is overjoyed but then overhears Susanna conspiring with Figaro and allows Figaro to be accused. The Countess is determined to go through with the conspiracy against her husband, and she and Susanna compose a letter to him confirming the rendezvous with Susanna that evening in the garden. During the trial it is revealed that Figaro is the long-lost son of Marcellina fathered by Bartolo who was abducted as a baby. Arriving just in time to see Figaro and Marcellina embracing, Susanna thinks her fiancé has betrayed her, but she is pacified when she learns the truth. When the two couples – Susanna and Figaro and Marcellina and Bartolo stand before the Count asking for his permission to marry, Susanna skilfully hands him the letter, sealed with a pin, confirming their rendezvous that evening.
Figaro finds out everything about the planned rendezvous between the Count and Susanna from Barbarina and since he is unaware that the rendezvous is a deception, he is preparing a night ambush. The Countess disguised as Susanna arrives, then Cherubino, who believing she is Susanna demands a farewell kiss, but it is the Count who gets the kiss. The Count returns with a slap, but instead of Cherubino he hits Figaro who is hiding in the dark. Still believing he is courting Susanna the Count gives her a ring, but then Figaro steps in. The fake Susanna leaves the garden and the Count disappears as well. Now comes the real Susanna dressed as the Countess. Figaro opens his heart to her and complains about the behaviour of her husband. He realises what is going on; he joins in the joke and declares his passion for Susanna in her Countess disguise. The Count returns to discover Figaro with his wife, or so he thinks, and explodes with rage. At that moment, the real Countess steps forward and reveals her identity. Ashamed, the Count asks her pardon. After many moments of agonizing doubt, she forgives him and both couples are reunited.