Figaro and Susanna, servants to the Count and Countess Almaviva, are making preparations on the morning of their wedding. When Susanna learns that the Count has given them the bedroom adjacent to his, she protests. She fears that the Count will use this proximity to exercise his right as a feudal lord to initiate the new bride to the ways of lovemaking, an intention he has already communicated to Susanna via her music teacher, Don Basilio. The Count’s designs anger Figaro, and when Susanna leaves, he promises a revenge that will preserve Susanna’s virtue.
Marcellina and her former employer Doctor Bartolo arrive with a plan to prevent Figaro’s marriage. Marcellina wants to marry Figaro herself and plans to do so by enforcing the terms of an unresolved contract for a loan she made to Figaro years earlier. Susanna returns and shares a contentious exchange with her rival.
Marcellina leaves and Cherubino arrives. The young page has been banished from the castle after the Count found him in a compromising position with Barbarina, the gardener’s daughter. The page is pleading with Susanna to intervene on his behalf when the Count pays a surprise visit. While Cherubino hides, Susanna refuses the Count’s propositions. When they hear Don Basilio approaching, the Count also hides until he overhears Basilio telling Susanna that Cherubino is suspected of flirting with the Countess. In the midst of his tirade about Cherubino’s indiscretions, the Count inadvertently uncovers the page from his hiding place. The confusion is interrupted by the arrival of Figaro. He and some villagers stage a tribute to the “fair and just” Count. The Count responds to the morning’s events by delaying the wedding until that evening and by sending the pageboy away to fill a position in his regiment.
Susanna is relaying the morning’s events to the Countess when Figaro enters to explain his plan, a diversion that Figaro asserts will ensure that his wedding proceeds as planned. He has sent an anonymous letter to the Count warning that the Countess is planning a tryst with a lover. Additionally, Susanna is to agree to the Count’s proposition for an illicit encounter, but Figaro has arranged for Cherubino to be disguised as a girl and sent in Susanna’s stead. Figaro retrieves Cherubino, and Susanna and the Countess dress him for the charade.
They are surprised by a knock on the door from the Count. Cherubino hides, locking himself in the closet. The jealous Count, angered by the anonymous letter, threatens to break into the closet, but when he and a reluctant Countess leave momentarily to obtain the necessary tools, Susanna takes Cherubino’s place in the closet. The page escapes, jumping out of the window. The Count and Countess return, and Susanna emerges from the closet. The Count begs forgiveness but defends his suspicions with the anonymous letter. The women admit the letter was fabricated by Figaro.
Figaro enters and denies knowing anything about the letter. Then Antonio, the gardener arrives, outraged that someone has jumped from the window into his flowers. As Susanna and the Countess discredit Antonio for being a drunkard, Figaro claims that it was he himself who jumped. With the Count’s suspicions renewed and confusion mounting, Marcellina arrives along with her cohorts and makes her claim for Figaro to either repay his debt to her or marry her.
Susanna and the Countess have created a new plan in which Susanna is to promise to meet the Count, but instead the Countess will go in disguise and reveal the Count’s infidelities. Susanna arranges the supposed rendezvous, but her efforts are nearly ruined when the Count overhears an exchange between her and Figaro. Don Curzio, the judge, oversees the trial between Marcellina and Figaro. Figaro claims that he cannot marry her because he requires his parents’ permission, and being an orphan, that is not possible. Figaro’s story of being kidnapped as an infant sounds familiar to Marcellina, and a birthmark on Figaro’s arm confirms that he is Marcellina’s long-lost son, the result of her affair with Doctor Bartolo. The proud parents embrace their son and their future daughter-in-law, and a double wedding is planned.
Meanwhile, Susanna and the Countess write a letter to the Count confirming the tryst that evening. They seal the letter with a pin. Barbarina and the village girls enter to bring flowers to the Countess. The Count and Antonio interrupt to reveal Cherubino dressed as a girl hiding amongst the crowd. Barbarina intercedes and convinces the Count to forgive Cherubino. Having found the page at last, the Count uses the opportunity to try to force Figaro into admitting what really happened in the Countess’s bedroom earlier in the day. The villagers begin the wedding procession. Before completing the ceremony, Susanna slips the Count the note sealed with the pin.
Figaro and Marcellina happen upon Barbarina in the garden searching for the pin she was meant to return to Susanna as confirmation of the tryst. Barbarina naively reveals her mission, and an enraged Figaro swears revenge for what he believes is his bride’s unfaithfulness. Figaro engages Bartolo and Basilio as witnesses and hides himself in order to catch Susanna with the Count. Marcellina returns with the Countess and Susanna, warning them that Figaro is hiding nearby. Marcellina hides, and Susanna and the Countess exchange clothes. Susanna hides, and the Countess, dressed as Susanna, awaits the Count’s arrival. Instead, Cherubino comes. Finding the supposed Susanna, he propositions her until the Count interrupts. Cherubino hides. The Count makes advances towards “Susanna” until Figaro intercedes. The Count flees and the Countess hides. Susanna, still pretending to be the Countess, steps forward, and Figaro recognizes his wife’s voice. The plot becomes apparent to him, but he plays along for a moment, until Susanna reveals her true identity, and both are reconciled.
Figaro and Susanna (still dressed as the Countess) stage a love scene for the Count’s benefit. The jealous Count calls for help, and one by one, everyone is extracted from hiding. The Count points to the woman he believes has betrayed him, but the real Countess steps forward, removing her disguise and unveiling the entire charade. The Count, overcome with guilt, is forgiven by the Countess. All couples are happily restored, and go off to enjoy the wedding festivities.