On Christmas Eve, Marcello paints and Rodolfo gazes at the Parisian rooftops. Marcello is about to sacrifice one of the sparse furnishings to the stove for warmth when Rodolfo has an inspiration: pages of his drama will warm them. Colline returns followed by Schaunard, who arrives with provisions. The friends are about to leave to dine out when Benoit, the landlord, comes for the rent. The bohemians trick him then throw him out, unpaid. Rodolfo stays behind to finish an article he is writing. A young woman knocks on the door and asks if she may light her candle; she returns moments later searching for her key. As they search, their hands touch. He tells her of his life as a penniless poet; she describes her modest existence as a seamstress. Rodolfo goes to the window and tells his friends below to meet at the Café Momus. He declares his love to Mimì, which she returns.
A holiday crowds mills about the Latin Quarter dominated by the Café Momus as the bohemians spend their money. They meet at the café and order dinner, after Rodolfo has presented Mimì to his friends. Musetta and Alcindoro, her elderly admirer, take the table adjoining the friends. Marcello avoids Musetta, with whom he has recently broken up, and she tries to attract his attention. She decides it is time to rid herself of Alcindoro and feigns a pain in her foot, sending him off for a new pair of shoes. The bohemians search their pockets to pay the bill until Musetta deposits it together with her own; Alcindoro will pay both bills on his return.
Parisians begin their daily routines during a February dawn. Mimì asks directions to a tavern where Marcello and Rodolfo are. She finds Marcello and tearfully appeals for him to speak with Rodolfo, who has left her because of her coquettishness; he agrees. Rodolfo admits to Marcello that he still loves her and cannot endure watching her health fail due to his inability to provide for her. Coughing and violent sobs betray Mimì’s presence. She says goodbye to Rodolfo and tells him they must part without bitterness, but they cannot go through with the separation and decide to stay together until spring.
Reminiscing about their broken love affairs, Marcello and Rodolfo try to work and appear pleased that their former companions are flourishing. Schaunard and Colline arrive with frugal provisions and a more cheerful outlook. At the height of the friends clowning, Musetta appears with news that Mimì is seriously ill. Rodolfo rushes to Mimì and brings her in. Musetta sends Marcello for a doctor. The lovers are alone and reminisce about their love. Marcello announces that a doctor is on the way for the now sleeping Mimì. Rodolfo soon notices a change has come over his friends, they already know what he only now realizes: Mimì is dead.