Winner was an only child, born in Hampstead, London, England, to Helen (née Zlota) and George Joseph Winner (1910–1975), a company director. His family was Jewish; his mother was Polish and his father of Russian extraction. Following his father's death, Winner's mother gambled recklessly and sold art and furniture worth around £10m at the time, bequeathed to her not only for her life but to Michael thereafter. She died aged 78 in 1984.
He was educated at St Christopher School, Letchworth, and Downing College, Cambridge, where he read law and economics. He also edited the university's student newspaper, Varsity (he was the youngest ever editor up to that time, both in age and in terms of his university career, being only in the second term of his second year). Winner had earlier written a newspaper column, 'Michael Winner's Showbiz Gossip,' in the Kensington Post from the age of 14. The first issue of Showgirl Glamour Revue in 1955 had him writing another film and showbusiness gossip column, "Winner's World". Such jobs allowed him to meet and interview several leading film personalities, including James Stewart and Marlene Dietrich. He also wrote for the New Musical Express.