She was born in London. Her mother, Amy Clotilda Howson, was a singer and actress, from a theatrical family. Her mother's father, C E Howson, worked for the London Lyceum Company, as Sir Henry Irving's Treasurer. Her father, Reginald Kenneth Johnson, was a colonial civil servant who spent much of his life working in Nigeria. Her father died when she was 11 years old, leaving debts. Her mother earned a living as a typist. Until Pamela was 22, the family lived at 53 Battersea Rise, Clapham, South London.

Pamela attended Clapham County Girls Grammar School, where she excelled at English, art history, and drama. After leaving school at the age of 16, Pamela took a secretarial course and later worked for several years at the Central Hanover Bank and Trust Company. She began her literary career by writing poems, which were published by Victor B. Neuburg in the Sunday Referee. In 1933, Pamela wrote to Dylan Thomas, who had also been published in the same paper, and a friendship developed. Marriage was considered, but the idea was ultimately abandoned.

In 1936 she married an Australian journalist, Gordon Neil Stewart. Their son Andrew was born in 1941, and a daughter, Lindsay, in 1944. Pamela and her husband Neil were divorced in 1949. In 1950, Pamela married the novelist C. P. Snow (later Baron Snow). Their son Philip was born in 1952.

She wrote 27 novels. Her first novel, This Bed Thy Centre, was published in 1935. Her last novel, A Bonfire, was published in the year of her death, 1981. Her themes centred on the moral responsibility of the individual in their personal and social relations. The fictional genres she used ranged from romantic comedy (Night and Silence Who is Here) and high comedy (The Unspeakable Skipton) to tragedy (The Holiday Friend) and the psychological study of cruelty (An Error of Judgement). She also wrote two detective novels, jointly with her first husband Neil Stewart, under the joint pseudonym, Nap Lombard. She wrote seven short plays, six of them in collaboration with C. P. Snow. She had published a number of critical works, short stories, verse, sociological studies, and a collection of autobiographical essays. She reviewed extensively for magazines and newspapers and broadcast on the BBC radio programme 'The Critics'.

She was a FRSL and received a CBE in 1975. She was awarded the honorary degrees of Hon. DLitt (Temple University, Philadelphia 1963; York University, Toronto; Weidner College, Chester, Pennsylvania) and Hon. DHL (Louisville, Kentucky). She was a Fellow of the Center for Advanced Studies at Wesleyan University, of Timothy Dwight College, Yale University and of Founders College, York University, Toronto and held visiting academic positions at other North American universities including Harvard, Berkeley, Haverford and Cornell.

C. P. Snow died in July 1980. Less than a year later, Pamela Hansford Johnson died in London. Her ashes were scattered on the river Avon, at Stratford upon Avon.

Novels

• This Bed Thy Centre (1935)
• Blessed Above Women (1936)
• Here Today (1937)
• World's End (1937)
• The Monument (1938)
• Girdle of Venus (1939)
• Too Dear for My Possessing (1940)
• The Family Pattern (1942)
• Winter Quarters (1943)
• The Trojan Brothers (1944)
• An Avenue of Stone (1947)
• A Summer to Decide (1948)
• The Philistines (1949)
• Catherine Carter (1952)
• An Impossible Marriage (1954)
• The Last Resort (1956)
• The Unspeakable Skipton (1959)
• The Humbler Creation (1959)
• An Error of Judgement (1962)
• Night and Silence Who is Here? (1963)
• Cork Street, Next to the Hatters (1965)
• The Survival of the Fittest (1968)
• The Honours Board (1970)
• The Holiday Friend (1972)
• The Good Listener (1975)
• The Good Husband (1978)
• A Bonfire (1981)
• Tidy Death (with Neil Stewart) as Nap Lombard (1940)
• The Grinning Pig (with Neil Stewart) as Nap Lombard (1943)

Critical works

• Thomas Wolfe: A Critical Study (1947)
• Ivy Compton-Burnett (Writers and their Work Series) (1951)
• Marcel Proust's Letters to his Mother, ed. G. D. Painter (includes essay)
• The Novels of Marcel Proust (1956)

Drama

• Corinth House (1950)
• Family Party (with C.P. Snow) (1951)
• Her Best Foot Forward (with C.P. Snow) (1951)
• The Pigeon with the Silver Foot (with C.P.Snow) (1951)
• Spare the Rod (with C.P.Snow) (1951)
• The Supper Dance (with C.P.Snow) (1951)
• To Murder Mrs Mortimer (with C.P.Snow) (1951)
• Six Proust Reconstructions (1957)

Sociology

• On Iniquity: some personal reflections arising out of the Moors Murders trial (1967)

Poetry

• Symphony for Full Orchestra (1934)

Translation

• The Rehearsal, by Jean Anouilh, with Kitty Black (1961)

Memoir

• Important To Me (1974)