The academy said it is recognizing Poitier for "extraordinary performances and unique presence on the screen" and for "representing the motion picture industry with dignity, style and intelligence throughout the world."
Academy president Frank Pierson made the announcement.
"When the academy honors Sidney Poitier," said Pierson, "it honors itself even more."
Poitier, who was born in Miami and grew up in the Bahamas, broke into feature films in 1950 as a black doctor subject to murder accusations by white racists in "From Whence Cometh My Help." In 1955, he played a troubled high school student in the groundbreaking "Blackboard Jungle."
He earned his first Oscar nomination in 1958, as Noah Cullen -- a black convict who escapes from prison shackled to a white man, played by Tony Curtis -- in "The Defiant Ones." He played Porgy in the 1959 movie version of "Porgy and Bess" and starred in the 1961 movie adaptation of Lorraine Hansberry's long-running Broadway play, "A Raisin in the Sun."
Poitier won the best actor Oscar in 1963 for his portrayal of Homer Smith -- an unemployed construction worker who stops at a farm worked by a group of nuns who believe he has been sent by divine providence to build them a new church.
In 1965, Poitier starred in the interracial romance, "A Patch of Blue," as a black man who befriends a blind white woman.
Poitier's career hit a high point in 1967, when he starred in three memorable movies -- "To Sir, with Love," "In the Heat of the Night" and "Guess Who's Coming to Dinner."
"In the Heat of the Night" won the Oscar for best picture, and Poitier's co-star -- Rod Steiger -- was named best actor.
"Guess Who's coming to Dinner" was nominated for best picture. Katharine Hepburn won for best actress and Spencer Tracy was nominated for best actor.
Poitier tried his hand at directing with the 1972 feature "Buck and the Preacher," a Western in which he co-starred with Harry Belafonte. He went on to direct such other features as "Uptown Saturday Night" (1974), "Let's Do It Again" (1975), "A Piece of the Action" (1977) and the Richard Pryor-Gene Wilder comedy "Stir Crazy" (1980).
His last directing assignment -- the 1990 family comedy "Ghost Dad" -- starred Bill Cosby as a man given a few extra days to settle his affairs after his untimely death in a car crash.
Poitier's most recent project was "The Last Bricklayer in America," a TV movie in which he played a man coping with the loss of his wife and the obsolescence of his profession -- who turns his life around when he becomes a role model for a 13-year-old.
According to a release issued by the academy, so many members of the Board of Governors made comments seconding Poitier's nomination for the honorary Oscar that Actors Branch Gov. Tom Hanks finally had to utter a wisecrack in order to cut off the kudos and bring the matter to a vote.
"When I was a young actor, I worked as a bellboy," said Hanks. "I carried Mr. Poitier's bags once, and he tipped me five bucks!"
Poitier joins a list of previous honorary Oscar winners that includes Michelangelo Antonioni, Henry Fonda, Akira Kurosawa, Sophia Loren, Paul Newman and James Stewart. He will receive the statuette at the 74th Academy Awards Presentation on March 24 at the Kodak Theatre in Hollywood.