One early morning, a yellow taxi pulls up at Tiffany & Co. on Fifth Avenue in New York City, from which elegantly dressed Holly Golightly (Audrey Hepburn) emerges. Standing outside the shop looking into the windows, she nibbles on pastry and drinks coffee she brought with her, then strolls home to go to bed. Outside her apartment, she fends off her date Sid Arbuck (Claude Stroud) from the disastrous night before. Later in the day she is awakened by new neighbor-tenant, Paul Varjak (George Peppard), ringing her doorbell to get into the building. The pair chat as she dresses to leave for her weekly visit to Sally Tomato (Alan Reed), a mobster incarcerated at Sing Sing prison. Tomato’s lawyer O’Shaughnessy pays her $100 a week to receive “the weather report.”
As she is leaving for Sing Sing, Holly is introduced to Paul’s “decorator”, wealthy older woman Emily Eustace Failenson (Patricia Neal), whom Paul nicknames “2E”. That night, Holly goes out onto the building’s fire escape to elude an over-eager date (Mel Blanc). She peeks into Paul’s apartment and sees 2E leaving money and kissing Paul goodbye. After 2E leaves, Holly enters Paul’s apartment and learns that he is a writer who has not had anything published since a book of vignettes titled, Nine Lives, five years before. Holly, in turn, explains that she is trying to save money in order to support her brother, Fred, when he gets out of the Army. The pair fall asleep, but are awakened when Holly has a nightmare about Fred and leaves the apartment. She later buys Paul a new typewriter ribbon to apologize and invites him to a party at her apartment. At the party, Paul meets her Hollywood agent, O. J. Berman (Martin Balsam), who describes Holly’s transformation from country girl into Manhattan socialite. He is also introduced to José da Silva Pereira (José Luis de Vilallonga), a rich Brazilian, and Rusty Trawler (Stanley Adams), a rich American.
In the days that follow, Paul and Holly become closer. One day, 2E enters Paul’s apartment, worried that she is being followed. Paul tells her that he will investigate and eventually confronts Doc Golightly (Buddy Ebsen), Holly’s husband. Doc explains that Holly’s real name is Lula Mae Barnes, whom he married when she was 13 (“going on 14″), and that he wants to take her back to Texas, as Fred will be returning from the Army. After Paul reunites Holly and Doc, she tells Paul the marriage was annulled; Doc is in denial over it. Holly asks Paul to accompany her and Doc to the bus station. There she tells Doc she is not returning. Doc reveals that Fred is returning soon and tells her that if she does not return, he will not support him when he returns. Holly still refuses, and tells him she plans for Fred to live with her in New York. Doc leaves broken-hearted.
After drinking at a club, Paul and Holly return to her apartment, where she drunkenly tells him that she plans to marry Rusty Trawler for his money. A few days later, Paul learns that one of his short stories has been accepted for publication. On the way to tell Holly, he sees the newspaper at her door, its headline stating that Trawler has married someone else. Holly and Paul agree to spend the day together, taking turns doing things that each has never done before. At Tiffany’s, Paul has the ring from Doc Golightly’s box of Cracker Jack engraved as a present for Holly. After spending the night together, he awakens to find that she is not in his apartment, nor has she returned to her apartment. When 2E arrives at his apartment later, Paul ends his relationship with her in a gallant manner. She calmly accepts, having earlier concluded that he and Holly are in love with each other.
Holly schemes to marry José for his money, which angers Paul, who has firmly decided on his love for her. After Holly and José return to her apartment to find a telegram notifying her of Fred’s death, she trashes her apartment in grief, her behavior disturbing José. Months later, Paul has moved out of the building. He is invited to dinner by Holly, who is leaving the next morning for Brazil to continue her relationship with José. However, they are soon arrested by police in connection with Sally Tomato’s drug ring and taken to the 19th precinct, where Holly spends the night in jail.
The next morning, Holly is released on bail with help from O.J. and finds Paul waiting with a taxi. He has her cat and a letter from José explaining he must end their relationship due to her arrest. Holly insists she will go to Brazil anyway and releases the cat from the taxi into the rain. Paul confronts Holly about his love and her behavior, then leaves the cab, tossing the ring he had engraved for her into her lap and telling her to examine her life. She quickly runs after Paul, who has gone looking for the cat, and together they find him, look into each other’s eyes, and kiss.