Born and educated in Plymouth, he ran a business with his brother in the city. The business, Winnicott Bros., was in ironmongery and hardware, but being partly wholesale it provided an element of social cachet. Elected a member of Plymouth Town Council, he was later alderman and twice mayor, in 1906 and 1921. His many other public duties and offices ranged from being a trustee of the Plymouth Savings Bank to presenting an illuminated address to the then Prince of Wales on his return from the Far East in 1922. He took a particular interest in public libraries and his name is perpetuated on the foundation stone of the City Library, which he laid in 1907. His knighthood, for public service, was bestowed in 1924 and he was made a freeman of the City in 1934.
From his early days he was associated with the King Street Wesleyan chapel where he was senior Chapel Steward and a Sunday School teacher. He is described in the Oxford DNB as having had 'a simple but deep Wesleyan religious faith'. When the Mutley chapel was built in 1880 he transferred his membership there and remained a steward for the rest of his life as well as being a circuit steward and holding 'most of the offices open in the Connexion'. In memory of his brother, also an alderman, in 1939 Winnicott gave £1,000 towards renovating King Street chapel. (Sadly King Street chapel was an early casualty of the blitz and Mutley chapel was closed and demolished in the 1970's.) He died at Plymouth on 31 December 1948.
His son, Donald Woods Winnicott (1896-1971), was educated at The Leys School and Jesus College, Cambridge. Encouraged by his father to read the Bible and make up his own mind on religious matters, he later reacted against his nonconformist background, but retained a sense of social responsibility. 'Coddled by a depressive mother', he became a distinguished though controversial paediatrician and psychoanalist, a disciple of Freud, and was the author of many publications. He died in London on 25 January 1971.