Hoffmann's muse hopes that he will forget his love for the singer Stella and devote himself henceforth to poetry.
Councillor Lindorf intercepts a letter from Stella to Hoffmann, promising him an assignation after the evening's performance of Don Giovanni, in which she is appearing, and enclosing her key. Taking possession of the letter and key, Lindorf announces that it will be he, not Hoffmann, who uses it later. He says he will also take Hoffmann's place in the lady's affections: he may be old and unattractive, but he is still vigorous and he can compel through fear.
The first act of Don Giovanni ends and students pour into the tavern, followed shortly by Hoffmann and his friend Nicklausse. Hoffmann is out of sorts and offers to cheer himself up and entertain the company by singing a song about the dwarf Kleinzach. In the midst of his account of the dwarf's physical peculiarities, however, he breaks off into a rhapsody about Stella's charms. His friends bring him back to earth and he finishes the song.
He notices Lindorf and accuses him of being his evil genius. Lindorf taunts him with being in love, and his friends avert a quarrel by praising their mistresses. Expressing his contempt for these ladies, Hoffmann promises to tell the stories of his own three loves.
The reception room in the house of the inventor Spalanzani
Spalanzani and his servant Cochenille are preparing for a ball to present Spalanzani's "daughter" Olympia to the world. Hoffmann, Spalanzani's pupil, arrives early and the inventor withdraws to leave Hoffmann alone with Olympia, who is sitting motionless behind a curtain. Finding him in rapt admiration of Olympia, Nicklausse hints broadly that he is in love with a doll, but Hoffmann refuses to listen. Coppélius, in search of Spalanzani, finds Hoffmann and sells him a pair of rosy spectacles through which Olympia appears more beautiful (and lifelike) than ever. He then confronts Spalanzani with a demand for payment for the eyes he made for Olympia and, to get rid of him, Spalanzani gives him a cheque on the firm of Elias, of whose bankruptcy he has just learnt. Olympia sings a brilliant song to entertain the guests, who go to supper, except for Hoffmann, who declares his love to Olympia, accidentally pressing a switch which causes her to run away.
Coppélius returns, furious at having been cheated, and hides in Olympia's bower. The guests reappear, the waltz begins and Hoffmann dances with Olympia, who whirls faster and faster until he falls and breaks his glasses. Cochenille manages to shepherd Olympia into her room, but sounds of smashing precede the appearance of Coppélius waving the broken pieces of the doll. All laugh at the deluded Hoffmann, who now realises that his love was an automaton.
As she sings to her own accompaniment on the piano, Antonia remembers happier days with Hoffmann, from whom her father has separated her, fearing that he may encourage her desire to sing. He begs her not to sing any more, and she obeys sadly. Unknown to Antonia, her father fears her resemblance to her mother, a famous singer who had died of a chest complaint exacerbated by singing. He goes out, telling his deaf servant to admit no one.
Frantz takes the opportunity to try his hand, unsuccessfully, at singing and dancing. His incomprehension of his master's orders causes him to admit Hoffmann and Nicklausse, and Hoffmann and Antonia have an ecstatic reunion. When she sings for him, he notes the signs of fever, and she tells him that her father has forbidden her to sing. Crespel returns, and Hoffmann hides and observes the visit of Dr Miracle: once more Frantz's deafness has prevented Crespel from keeping out an unwelcome visitor.
Believing that Dr Miracle killed his wife, and fearing his influence on Antonia, Crespel refuses to let him examine her, but Dr Miracle proceeds to examine her in absentia and when he orders her to sing, her voice can be heard from her room. Crespel rejects his medicines in horror and finally gets rid of him. Hoffmann now understands the nature of Antonia's malady and begs her to sing no more and she agrees reluctantly, as he leaves to avoid her father.
Dr Miracle appears behind Antonia, enticing her with the delights of a career as a singer and accusing Hoffmann of wanting to bury her in domesticity. When he summons up the voice of her mother which seems to be urging her to sing, she joins in an outpouring of song, collapses and dies.
A palace overlooking the Grand Canal in Venice
Nicklausse and the courtesan Giulietta sing the barcarolle. Schlemil, Giulietta's discarded lover, broods over Hoffmann's apparent success with Giulietta. Hoffmann derides the notion that he might fall in love with such a woman, but is overheard by her protector Dapertutto, who prepares to ensnare him.
He uses a huge diamond to entice Giulietta to obtain for him not the shadow (as in the case of Schlemil) but the reflection of Hoffmann. The jealous Schlemil challenges Hoffmann to a duel, but is killed when Dapertutto gives Hoffmann supernatural assistance. Nicklausse warns Hoffmann that he must flee, but he is now infatuated with Giulietta and refuses. Giulietta promises to follow him, but persuades him to leave his reflection with her. Dapertutto decides to remove Nicklausse by poisoning him, but it is Giulietta who drinks the poison. Her jester, Pitichinaccio, seizes the diamond.
Hoffmann is completely drunk and when his muse appears, he promises to be hers alone. When Stella comes to find him, he rejects her, and at the suggestion of Nicklausse, she leaves on the arm of Lindorf.