Sandra Annette Bullock was born in Arlington, Virginia, the daughter of Helga D. Meyer (1942–2000), a German opera singer and voice teacher, and John W. Bullock (born 1925), a voice coach and executive from Alabama. Bullock's maternal grandfather was a rocket scientist from Nuremberg, Germany. Bullock lived in Fürth until age twelve, where she sang in the opera's children's choir at the Staatstheater Nürnberg. She frequently traveled with her mother on her opera tours, and lived in Germany and other parts of Europe for much of her childhood. She is fluent in German. Bullock studied ballet and vocal arts as a child, taking small parts in her mother's opera productions. Bullock has a sister, Gesine Bullock-Prado (born 1970).

Bullock attended Washington-Lee High School, where she was a cheerleader, participated in high school theater productions, and dated a football player. She graduated in 1982 and enrolled in East Carolina University in Greenville, North Carolina. She left East Carolina during her senior year in the spring of 1986, only three credits short of graduating, to pursue an acting career. She moved to Manhattan to pursue auditions and supported herself with a variety of jobs including bartender, cocktail waitress and coat checker.

Bullock later completed her coursework at East Carolina University.

While in New York, Bullock took acting classes at the Neighborhood Playhouse. She appeared in several student films, and later landed a role in an Off-Broadway play No Time Flat. Director Alan J. Levi was impressed by Bullock's performance and offered her a part in the made-for-TV movie Bionic Showdown: The Six Million Dollar Man and the Bionic Woman (1989). After filming the TV movie, Bullock stayed in Los Angeles and was cast in a series of small roles in several independent films as well as in the lead role of the short-lived NBC television version of the film Working Girl (1990). She later appeared in several films, such as Love Potion No. 9 (1992), The Thing Called Love (1993) and Fire on the Amazon (in which she agreed to appear topless if the camera did not show that much; she covered herself with duct tape, which apparently was somewhat painful to remove).