Garbo was born Greta Lovisa Gustafsson in Stockholm, Sweden, the youngest of three children of Karl Alfred Gustafsson and Anna Lovisa Johansson. When Garbo was 14 years old, her father, to whom she was extremely close, died. She was forced to leave school and go to work. Her first job was as a soap-lather girl in a barbershop. She then became a clerk at the department store PUB in Stockholm, where she would also model for newspaper advertisements. Her first motion picture aspirations came when she appeared in two short film advertisements (the first for the department store where she worked). They were eventually seen by comedy director Erik Arthur Petschler and he gave her a part in his upcoming film Peter the Tramp in 1922.

From 1922 to 1924, she studied at the prestigious Royal Dramatic Theatre in Stockholm. While there, she met director Mauritz Stiller. He trained her in cinema acting technique, gave her the stage name "Greta Garbo", and cast her in a major role in the silent film Gösta Berlings Saga (The Story of Gösta Berling) in 1924, a dramatization of the famous novel by Nobel Prize winner Selma Lagerlöf. She starred opposite Swedish film actor Lars Hanson and then appeared in the German film Die Freudlose Gasse - The Joyless Street.

She and Stiller were brought to Metro-Goldwyn-Mayer by Louis B. Mayer when Gösta Berlings Saga caught his attention. On viewing the film, Mayer was impressed with Stiller's direction, but was much more taken with Garbo's acting and screen presence. According to Mayer's daughter, Irene, with whom he screened the film, it was the gentle feeling and expression that emanated from her eyes which so impressed her father.

The most important of Garbo's silent movies were The Temptress (1926), Flesh and the Devil (1926), and Love (1927). She starred in the latter two with the popular leading man John Gilbert. Her name was linked with his in a much publicized romance, and she was said to have left him standing at the altar in 1926, when she changed her mind about getting married.

Having achieved enormous success as a silent movie star, she was one of the few actors who made the transition to talkies, though she delayed the shift for as long as possible. Her film The Kiss (1929) was the last film MGM made without dialogue (it used a soundtrack with music and sound effects only). Her voice was first heard on screen in Eugene O'Neill's Anna Christie (1930), which was publicized with the slogan "Garbo Talks". The movie was a huge success. In 1931 Garbo made a German version of the movie.

Garbo appeared as the World War I spy Mata Hari (1931). She was next part of an all-star cast in Grand Hotel (1932) in which she played a Russian ballerina. She then had a contract dispute with MGM. She signed a new contract in July 1932. She exercised her new control by getting her leading man in Queen Christina (1933), Laurence Olivier, replaced with Gilbert. In 1935, David O. Selznick wanted her cast as the dying heiress in Dark Victory, but she insisted on doing Tolstoy's Anna Karenina.

Her role as the doomed courtesan in Camille (1936), directed by George Cukor, would be regarded by Garbo as her finest acting performance. She then starred opposite Melvyn Douglas in Ninotchka (1939), directed by Ernst Lubitsch. Ninotchka was a successful attempt at lightening Garbo's image and making her less exotic, by the insertion of a scene in a restaurant in which her character breaks into uninhibited laughter which subsequently provided the film with its famous tagline, "Garbo laughs!".

Garbo was nominated for an Academy Award for Anna Christie (1930), Romance (1930), Camille (1937) and Ninotchka (1939).

Garbo was considered one of the most glamorous movie stars of the 1920s and 1930s. She was also famous for shunning publicity, which became part of her mystique. Except at the very beginning of her career, she granted no interviews, signed no autographs, attended no premieres, and answered no fan mail.

Garbo lived the last years of her life in absolute seclusion. She died in New York Hospital on April 15, 1990, aged 84, as a result of pneumonia and renal failure, which had shut down her stomach and kidneys. She was cremated and her ashes were finally interred after a long legal battle at the Skogskyrkogården Cemetery in her native Stockholm. For her contributions to cinema, she has a star on the Hollywood Walk of Fame at 6901 Hollywood Boulevard. In addition, in September 2005, the United States Postal Service and Swedish Posten jointly issued two commemorative stamps bearing her likeness.