Dr. Coppélius is a doctor who has made a life-size dancing doll. It is so lifelike that Franz, a village youth, becomes infatuated with it and sets aside his heart's true desire, Swanhilda. She shows him his folly by dressing as the doll, pretending to make it come to life and ultimately saving him from an untimely end at the hands of the inventor.

Act I
The story begins during a town festival to celebrate the arrival of a new bell. The town crier announces that, when it arrives, anyone who becomes married will be awarded a special gift of money. Swanilda and Franz plan to marry during the festival. However, Swanilda becomes unhappy with Franz because he seems to be paying more attention to a girl named Coppélia, who sits motionless on the balcony of a nearby house. The house belongs to a mysterious and faintly diabolical inventor, Doctor Coppélius. Although Coppélia spends all of her time sitting motionless and reading, Franz is mesmerized by her beauty and is determined to attract her attention. Still upset with Franz, Swanilda shakes an ear of wheat to her head: if it rattles, then she will know that Franz loves her. Upon doing this, however, she hears nothing. When she shakes it by Franz's head, he also hears nothing; but then he tells her that it rattles. However, she does not believe him and runs away heartbroken.

Later on, Dr. Coppelius leaves his house and is heckled by a group of boys. After shooing them away, he continues on without realizing that he has dropped his keys in the melée. Swanilda finds the keys, which gives her the idea of learning more about Coppélia. She and her friends decide to enter Dr. Coppelius' house. Meanwhile, Franz develops his own plan to meet Coppélia, climbing a ladder to her balcony.

Act II
Swanilda and her friends find themselves in a large room filled with people. However, the occupants aren't moving. The girls discover that, rather than people, these are life-size mechanical dolls. They quickly wind them up and watch them move. Swanilda also finds Coppélia behind a curtain and discovers that she, too, is a doll.

Dr. Coppelius returns home to find the girls. He becomes angry with them, not only for trespassing but for also disturbing his workroom. He kicks them out and begins cleaning up the mess. However, upon noticing Franz at the window, Coppélius invites him in. The inventor wants to bring Coppélia to life but, to do that, he needs a human sacrifice. With a magic spell, he will take Franz's spirit and transfer it to Coppélia. After Dr. Coppelius proffers him some wine laced with sleeping powder, Franz begins to fall asleep. The inventor then readies his magic spell.

However, Dr. Coppelius did not expel all the girls: Swanilda is still there, hidden behind a curtain. She dresses up in Coppélia's clothes and pretends that the doll has come to life. She wakes Franz and then winds up all the mechanical dolls to aid their escape. Dr. Coppelius becomes confused and then saddened when he finds a lifeless Coppélia behind the curtain.

(Note: In some Russian versions of the ballet, after getting caught, Swanhilda confesses to Dr. Coppelius about what she and her friends did and her situation with Franz. Coppelius decides to forgive Swanhilda and teach her how to act like a doll coming to life to fool Franz, thus ending Act 2 on a happier note.)

Act III
Swanilda and Franz are about to make their wedding vows when the angry Dr. Coppelius appears, claiming damages. Dismayed at having caused such an upset, Swanilda offers Dr. Coppelius her dowry in return for his forgiveness. However, Franz tells Swanilda to keep her dowry and offers to pay Dr. Coppelius instead. At that point, the mayor intervenes and gives Dr. Coppelius a bag of money, which placates him. Swanilda and Franz are married and the entire town celebrates by dancing.