The Countess, Suzanne, and Figaro agree upon a two-fold plan to thwart the Count and return his affections to his wife: Figaro provokes the Count's jealousy by giving him an anonymous note warning that the Countess has a lover; Figaro also proposes that they send Cherubino, disguised as Suzanne, to meet the Count that evening. Cherubino arrives, but when the Count knocks on the door, he hides in the closet. The Count is upset by the note he has just received, and his suspicions are raised further when Cherubino makes a noise in the closet. Although the Countess says it is only Suzanne in the closet, the Count does not believe her. He leaves the room, accompanied by the Countess, to get tools to break down the door. While they are gone, Suzanne takes Cherubino's place in the closet, and he jumps out the window. When the Count opens the door, he finds only Suzanne.

Figaro comes in and is forced to cover himself when the Count finds out that he was behind the note. Marceline arrives on Figaro's heels, proclaiming that she has a note that says that Figaro must either repay a debt or marry her. The Count declares that the matter will be heard by the court.

Alone, the Countess and Suzanne reject Figaro's plan. They decide that the Countess will dress up as Suzanne and go meet the Count. The Countess forbids Suzanne to tell Figaro of the new plot.