Act III

At the start of Act III, the Count is conflicted about whether to side with Marceline or Figaro. Despite Suzanne agreeing to meet him that evening, the Count doubts her intentions because he realizes she has informed Figaro about his seduction plan. Consequently, he opts to support Marceline's case.

During the trial, a smudge on a key word in the contract between Marceline and Figaro makes its meaning ambiguous. After multiple readings, the Count rules that Figaro must either pay Marceline back within the day or marry her. Figaro attempts to evade this decision by claiming he cannot marry without his parents' consent. He explains that he was kidnapped by gypsies as a child and thus does not know who his parents are. He then reveals a mark on his arm, prompting Marceline to recognize him as her and Bartholo's illegitimate son. Marceline joyfully embraces her long-lost son, but Bartholo is repelled because he dislikes Figaro. Suzanne arrives with money given to her by the Countess to help Figaro repay the debt, but Marceline returns it to Figaro as his dowry. The Countess, Suzanne, and Figaro then persuade Bartholo to marry Marceline.

Act IV

Figaro asks Suzanne not to meet with the Count, and she agrees. However, when Suzanne informs the Countess of her decision, the Countess explains that she needs Suzanne's assistance to regain her husband's affection. Together, they write a note to the Count, requesting a meeting under the elm trees. During the double wedding ceremony, Suzanne hands the note to the Count. Figaro sees the Count reading it but does not realize it is from Suzanne. A casual remark eventually reveals to him the note's sender and the meeting place. Figaro becomes jealous and furious but, following Marceline's advice, decides to attend the rendezvous in secret.

Act V

The Countess, disguised as Suzanne, arranges to meet the Count, Cherubino, and Fanchette, who have their own plans. They all hide in the pavilion on the left, where Marceline is also concealed. The Count tries to seduce "Suzanne," which infuriates Figaro, who is watching from a distance. Figaro intervenes to stop the Count, causing the Count to flee. The Countess then enters the pavilion on the right. Figaro encounters Suzanne, who is disguised as the Countess, but he quickly recognizes her voice. To retaliate against Suzanne, he suggests a tryst with the "Countess." When Suzanne realizes that Figaro has recognized her, she explains why she arranged the meeting with the Count. The Count returns and sees "Suzanne" with Figaro, becoming enraged. Suzanne escapes into the pavilion on the left, while the Count apprehends Figaro and arrests him. Figaro pretends that he was about to have an affair with the Countess. The Count enters the pavilion to drag his wife out and force her to confess her infidelity in front of everyone. However, he pulls out Cherubino, Fanchette, and Marceline instead. Suzanne emerges but hides her face, making the Count still believe she is the Countess. Everyone kneels before the Count, pleading for him to forgive his wife. Although he initially refuses, the real Countess, still disguised, steps out from the other pavilion and joins the group. Realizing he has been fooled by the dual disguises, the Count finally understands the ruse. The play concludes with Figaro and Suzanne getting married and becoming wealthy with a triple dowry.