Mrs. Higgins is in her drawing room when her parlor-maid enters and informs her that Pickering and Higgins are downstairs calling the police. Mrs. Higgins sends the parlor-maid upstairs to inform Eliza that the men are here and that she should not come until she is called. Higgins enters and explains that he is frantic that Eliza has left-he cannot find anything and now has nobody to remind him of his appointments. Mrs. Higgins scolds her son for calling the police as if Eliza were a lost parcel.
The parlor-maid announces Mr. Doolittle, who enters in a fancy waistcoat. Doolittle claims that Higgins has ruined his happiness. Higgins says that this is impossible because he only gave him a small amount of money, and because he has had only two conversations with him since the first one. Doolittle explains that Higgins wrote a letter to a man named Ezra D. Wannafeller saying that Doolittle was the most original moralist in England, and the man died and left his millions to Doolittle-partially to show that the Americans do not regard class in the same way that the English do. Doolittle says that he is miserable after being made a gentleman: everybody asks him for money, and he does not have the nerve to forsake his new wealth and station.
Mrs. Higgins says that at least he now can provide for his daughter. Higgins objects to this idea, saying that he bought her for five pounds. Mrs. Higgins reveals that Eliza is upstairs, having come upset very early in the morning. Mrs. Higgins censures them for not admiring Eliza or telling her she did a good job.
When Eliza comes down, she looks self-possessed and very much at home. She uses the genteel accents that Higgins has taught her. Higgins is furious and claims that he has made her what she is. Pickering assures Eliza that he does not think of her as just an experiment, and she expresses her gratitude to him for everything, especially for teaching manners to her. She adds pointedly says that Higgins could not have taught her such manners.
Eliza says that the difference between a lady and a flower-girl is not in anything that she does but in how she is treated. Pickering always treated her like a lady, whereas Higgins has treated her like dirt. Higgins claims in response that he treats everyone like dirt.
Doolittle tells his daughter that he is marrying her mother. Doolittle is nervous, and he asks Pickering to come to help see him through the wedding. Mrs. Higgins decides to go as well, leaving Higgins and Eliza alone. Eliza says that she will not come back because Higgins only wants her to pick up his slippers and the like. Higgins says that he cannot change his own manners, but at least he is democratic: again, he says he treats everyone as if they were of the lower class. Eliza says that she shall not be passed over and that she can do without Higgins. Higgins says that he needs to determine if he can do without her, since he has grown accustomed to having her around. Eliza claims that he should not have taught her anything because it only leads to trouble, but Higgins claims that all creation leads to trouble.
Eliza says that she is holding out for something more, adding that Freddy is infatuated with her and writes her letters every day. She says that she participated in the experiment because she had come to care for Higgins, and all she wanted was a little kindness. She had not forgotten the social and economic gaps between them. Higgins idealizes the lower-class life, saying that you work until you are inhuman, then you squabble or make love or drink until you fall asleep. He also says that Eliza needs too much attention. She says that to assert her independence she will marry Freddy or become a teacher of phonetics. He finds her spirit to be attractive and says that she is no longer a woman but a tower of strength. He suggests that she live with him and Colonel Pickering, the three of them together as bachelors.
Mrs. Higgins returns dressed for the wedding, and she takes Eliza with her. Higgins asks her to run his errands for him, including one to buy some cheese and ham. She says a final goodbye to him, and he seems confident that she will follow his command.
The onstage drama ends, and Shaw adds, in an epilogue, that Eliza recognizes Higgins as predestined to be a bachelor-and that she marries Freddy instead. (This was somewhat of a scandal, but the fact that Eliza's father had become a social success made it less hard on the Eynsford Hills.) With a gift from Colonel Pickering, Eliza opens up a flower shop. The only person truly bothered by this state of affairs is Clara, who figures that the marriage will not help her own marriage prospects. But Clara began to read H.G. Wells and travel in the circles of his fans, and she decides to begin working in a furniture shop herself in the hopes that she might meet Wells (because the woman who owns the shop is also a fan of his). Freddy is not very practical, and he and Eliza have to take classes in bookkeeping to make their business a success. But they do make it a success, and they live a fairly comfortable life.
The mythological themes that give the title to this play are at their strongest in this act. The audience learns conclusively that Higgins truly views himself as Eliza's creator.
Shaw sets up a strange, almost Freudian symmetry between Higgins and his mother on the one hand and Eliza and her father on the other. Higgins gives one of his reasons for never marrying as his too great respect for his mother. Her love of beauty, art, and philosophy has led her son to value Milton's poetry and his own universal alphabet more highly than he could a relationship with a woman. From Eliza's perspective, Higgins seems too much like her father in that neither of them really need her. Eliza genuinely cares about Higgins and is stung by the idea that he needs her no more than he needs his slippers. This represents the same sort of nonchalance with which Doolittle sells his only daughter in Act II for a five-pound note. Paternal relations and romantic relations, should be stronger than this. But Higgins's respect for his mother seems to interfere with his own life.
Shaw's description of the final state of affairs shows an interesting perspective on love. Freddy was infatuated with Eliza and remains so, but it is unclear what her feelings are towards him. She certainly likes him, but she continues to feel the most passionately (mostly in anger) about Higgins. She wishes that she could get him on a "desert island" just to see him make love like any other man-but this remains a private fantasy which Shaw dismisses as ultimately unimportant. The social mores of the characters tend to favor balanced and practical love over passionate, romantic love.
Despite the fact that Shaw moved away from Ireland at a young age, he is a quintessentially Irish writer. (See, for instance, John Bull's Other Island Show.) Read in the light of the imperial relationship between England and Ireland, Eliza's final declaration of independence might have a political connotation, especially since language and location have been intertwined from the beginning. The fact that the English forced their language on the Gaelic-speaking Irish, after invading Ireland, has particular bearing on this play, where we witness a male forcibly teaching a female to speak. (One might consider the possibility of similar themes of colonization and intrusion that involve reshaping language in Shakespeare's (otherwise very different play) The Tempest and, much later, Beckett's Endgame.) Like Shakespeare's Caliban, Eliza may see a significant benefit of her newly-acquired language as the ability to curse her "master" with fluency. And Ireland (like many countries) is feminized in the Irish popular imagination, represented by female names like Erin and "Kathleen Ni Houlihan," while in colonial narratives the conqueror is usually portrayed as male. Pygmalion was produced only four years before the 1916 Easter Uprising, and Eliza's demand for self-determination, after rising into her own social maturity, may reflect the Irish nationalist cause.