The play opens on a morning in Lady Windermere’ residence in London, who prepares for her coming of age birthday ball. Around tea time, Lady Windermere is visited by Lord Darlington, a friend of hers who starts complimenting her in a manner that is considered improper by Lady Windermere. Another character comes, The Duchess of Berwick, and Lord Darlington leaves shortly after the Duchess arrives.
The Duchess tells Lady Windermere that the Society talks about Lady Windermere’s husband apparent infidelity. The Duchess tells Lady Windermere how her husband gives large sums of money to a woman of questionable character named Mrs. Erlynne and that the rumor of his infidelity already spread through the London society.
After the Duchess leaves, Lady Windermere starts to look for evidence to see if what she has heard is true or not. Lady Windermere searches her husband’s bank book but finds nothing wrong with them. She soon finds another bank book, with a lock on it and when she breaks the lock, Lady Windermere finds that her husband gave large sums of money to Mrs. Erlynne just as the Duchess said.
When Lord Windermere comes home, Lady Windermere confronts him about what she has found but her husband denies cheating on her. What is more, he even suggests that Lady Windermere should send an invitation to her birthday party to Mrs. Erlynne but Lady Windermere refuses categorically.
Lady Windermere leaves the room and Lord Windermere reveals that he is protecting his wife by hiding Mrs. Erlynne’s identity, knowing that if his wife were to find who she really is, the shame would kill her.
Act two opens in the Windermere’s drawing room during the ball. Guests start to arrive and Lady Windermere tries to avoid Lord Windermere. Lord Augustus Lorton, one of Lord Windermere’s friends comes as well and asks Lord Windermere about the rumors regarding him and Mrs. Erlynne. Lord Windermere tells him that the rumors are lies and Lord Augustus then tells his friend that he likes Mrs. Erlynne and even thinks about marrying her. Lord Windermere assures his friends that Mrs. Erlynne will also attend the ball and then he will have the chance to talk with her.
Lord Windermere tries to talk with his wife about Mrs. Erlynne but she refuses to listen to him. Mrs. Erlynne arrives at the ball and she is welcomed coldly by Lady Windermere who leaves soon after Mrs. Erlynne’s arrival.
Lord Darlington follows her and confesses his love for her while also proposing to run away with him. Lady Windermere refuses to give her answer so Lord Darlington sets an ultimatum, telling Lady Windermere that he will leave the next day and they will never see each other again.
Later that night, when the guests started to leave, Lady Windermere takes the decision to run away with Lord Darlington so she leaves a note for Lord Windermere explaining what she was going to do. The note is found by Mrs. Erlynne who immediately goes after Lady Windermere to try and stop her from running away with Lord Darlington. During a monologue, it is revealed that Mrs. Erlynne is actually Lady Windermere mother and she has done the same mistake her daughter is about to do.
Mrs. Erlynne finds her daughter at Lord Darlington’s house and tries to convince her to return to her husband. At first, Lady Windermere refuses to listen to Mrs. Erlynne but when Mrs. Erlynne starts to talk about Lady Windermere’s child, she decides to return home.
The two women are forced to hide when they hear Lord Darlington and other men returning home. Lord Windermere and Lord Arthur are also there and they begin talking about women. When Lord Windermere prepares to leave, he notices a fan belonging to his wife on a table and a quarrel breaks between Lord Windermere and Lord Darlington. Lady Windermere escapes unnoticed with the help of Mrs. Erlynne who reveals herself instead.
The events presented in the last act take place a day after Lady Windermere escaped from Lord Darlington’s house. Lord Windermere and Lady Windermere reconciled and decided to take a holiday away from their friends. Mrs. Erlynne arrives but Lord Windermere refuses to let her meet his wife. At Lady Windermere’s insistence, however, the two women meet and Mrs. Erlynne tells her that she will be going abroad. Mrs. Erlynne asks for a photograph of Lady Windermere and her child and while Lady Windermere leaves the room, Mrs. Erlynne forbids Lord Windermere from revealing the truth about her identity to Lady Windermere.
Lady Windermere returns and gives Mrs. Erlynne a photograph while also promising not to tell the truth about the events that took place a night before.
Lord Augustus also enters and Mrs. Erlynne asks him to accompany her so that she could explain properly what has happened the night before. After a short time, Lord Augusts returns and announces that he and Mrs. Erlynne will get married and live outside England.