Sidney Poitier was the youngest of seven surviving children, born to Evelyn (née Outten) and Reginald James Poitier, Bahamian farmers who owned a farm on Cat Island.
The family would travel to Miami to sell tomatoes and other produce. Reginald also worked as a cab driver in Nassau, Bahamas.
Poitier was born in Miami while his parents were visiting. His birth was two months premature and he was not expected to survive, but his parents remained in Miami for three months to nurse him to health. Poitier grew up in the Bahamas, then a British Crown colony. Because of his birth in the United States, he automatically received American citizenship.
Poitier's uncle believed that the Poitier ancestors on his father's side had migrated from Haiti, and were probably among the runaway slaves who established maroon communities throughout the Bahamas, including Cat Island. He noted that Poitier is a French name, and that there were no white Poitiers from the Bahamas. However, there had been a white Poitier on Cat Island; the name came from planter Charles Leonard Poitier of English heritage who had immigrated from Jamaica in the early 1800s. In 1834, his wife's estate on Cat Island had 86 slaves, 39 men and 47 women. The slaves kept the name Poitier, a name that had been introduced into England during the Norman conquest in the 11th century.
Poitier lived with his family on Cat Island until he was 10, when they moved to Nassau. There, he was exposed to the modern world, where he saw his first automobile, first experienced electricity, plumbing, refrigeration, and motion pictures. He was raised a Roman Catholic but, later became an agnostic with views closer to deism.
At the age of 15, he was sent to Miami to live with his brother's large family. At the age of 16, he moved to New York City and held a string of jobs as a dishwasher. A waiter sat with him every night for several weeks helping him learn to read the newspaper. In 1943, he lied about his age and enlisted in the Army during World War II. He only served briefly as a mental hospital attendant and feigned insanity to get discharged, but dropped this tactic. After talking to a psychiatrist, Poitier was eventually granted release from the Army, after which he worked as a dishwasher until a successful audition landed him a spot with the American Negro Theater.