Directed by British director Steve McQueen, the film is based on a true story and stars Chiwetel Ejiofor as Solomon Northup, a free man who was kidnapped into slavery in the South. It is the first film directed by a black filmmaker to win the best picture Oscar.
Other nominees Sunday were: "American Hustle," ''Captain Phillips," ''Dallas Buyers Club," ''Gravity," ''Her," ''Nebraska," ''Philomena," and "The Wolf of Wall Street."
Matthew McConaughey has won the Academy Award for best actor for his performance as a desperate and determined AIDS patient in "Dallas Buyers Club."
McConaughey lost some 40 pounds for the role, which capped a remarkable recent career transformation for the 44-year-old actor, once a regular in lightweight romantic comedies. It was his first Oscar nomination; he won the Golden Globe for best actor in a drama earlier this year.
The other nominees Sunday night were: Christian Bale, "American Hustle"; Bruce Dern, "Nebraska"; Leonardo DiCaprio, "The Wolf of Wall Street"; and Chiwetel Ejiofor, "12 Years a Slave."
Cate Blanchett has won the Academy Award for best actress for her bravura performance as a fragile socialite experiencing a meltdown in Woody Allen's "Blue Jasmine."
Blanchett had been deemed the front-runner from the very beginning of the Oscar season. It was the sixth Oscar nomination for the Australian actress and her second win, though her first in the leading actress category. Previously she won the 2005 supporting actress trophy for "The Aviator."
The other nominees Sunday night were: Amy Adams, "American Hustle"; Sandra Bullock, "Gravity"; Judi Dench, "Philomena"; and Meryl Streep, "August: Osage County."