Enid Mary Blyton was born on 11 August 1897 at 354 Lordship Lane, East Dulwich, London. She was the first child of Theresa Mary Harrison (1874-1950) and Thomas Carey Blyton (1870-1920), a salesman of cutlery, later when the family had moved to the nearby suburb of Beckenham, they had two sons more, Hanly (b. 1899), and Carey (b. 1902). She adored her father during her childhood years, but when she was 13, her father left home, and she only saw him for one day every month. Her father's departure had a huge effect on her, impeding her growth and making her ill. From 1907 to 1915, Enid Mary was educated at St. Christopher's School in Beckenham. She was a talented pianist, but gave up her musical studies when she trained as a teacher at Ipswich High School. She taught for five years at Bickley, Surbiton and Chessington, writing in her spare time.

Enid Mary's first book, "Child Whispers", a collection of poems, was published in 1922, when met the handsome Major Hugh Alexander Pollock (1888-1971), who was marked by the divorce from his first wife, Denis Thatcher, to whom he lost to another man, while he was in the First World War. She wrote in her diary soon after meeting him: "I want him for mine." On 28 August 1924, Enid Mary became the second wife of Hugh Pollock, editor of the book department in the publishing firm of George Newnes, which published two of her books that year. The couple moved to Buckinghamshire and eventually they moved to a house in Beaconsfield, know as Green Hedges. At the beginning of the 1930s, she had an experience of a spiritual crisis, but she decided against converting to Roman Catholicism from the Church of England because she had felt it was "too restricting". The Pollocks had two children: Gillian (1931-2007) and Imogen Mary (b. 1935), who were baptised into the Anglican faith. Shortly after the birth of their daughters, she started writing her first children's series of books based on recurring characters and designed for different age groups. Described as a "one-woman fiction machine", she was the author of a host of legendary characters, including "The Famous Five", "The Secret Seven" and, most famously, "Noddy", "Big Ears" and the other inhabitants of Toyland. She used to sign her books with her maiden name, "Enid Blydon", and her married name, "Mary Pollock".

While her career was a success and she enjoyed with her maternity, the relationship with her husband was in difficulties by his suspicions of her infidelity, and when the Second World War began, the Pollocks' marriage was irretrievably broken. In that time Hugh Pollock met the writer Ida Crowe, his future third wife, and in 1941, Enid Mary also met her future second husband, Kenneth Fraser Darrell Waters (1892-1967), a London surgeon. Finally, Hugh asked for a divorce and Enid Mary acepted, he agreed to be identified as the "guilty" party in the divorce in return for an amicable separation and access to their daughters, who were 12 and 8. The divorce being granted in October 1943, Enid Mary married on 20 October 1943 at the City of Westminster register office, and Hugh also married a few days later (Hugh and Ida Pollock, had a daughter Rosemary Pollock, also a writer). But after the divorce and new marriages, Enid Mary decided that the best thing for her daughters, was not to have contact with his father, whom they had not seen much during the war. She even changed her daughter's surname to Darrell Waters. The relationship with her ex-husband became increasingly tense, and she forbade her editors and friends to work with her ex-husband, who declared bankrupt in 1950, blaming his ex-wife of his financial situation.

Enid Mary moved smoothly into her role as a devoted doctor's wife, living with him and her two daughters at the famous Green Hedges. Her literary output was of an estimated 700 books over roughly 40 years. She was very happy in her second marriage, and when her second husband died in 1967, she became increasingly ill. Afflicted by Alzheimer's disease, she was moved into the Greenways Nursing Home, 11 Fellows Road, Hampstead, London, where on 28 November 1968 she died, aged 71, and was cremated at the Golders Green Crematorium where her ashes remain.