Geoffrey Keynes was the son of John Neville Keynes, an economics lecturer at the University of Cambridge and Florence Ada Brown, a successful author and a social reformer. His older brother was the economist John Maynard Keynes and his sister Margaret married the Nobel Prize–winning physiologist Archibald Hill.
He graduated from Pembroke College, Cambridge, and then qualified as a surgeon with the Royal College of Surgeons in London. He served as a Lieutenant in the Royal Army Medical Corps during World War I and then worked as a consultant surgeon, becoming an expert in blood transfusion.
He maintained a passionate interest in English literature all his life and devoted a large amount of his time to literary scholarship and the science of bibliography. He was a leading authority on the literary and artistic work of William Blake and "was instrumental in establishing Blake as a central figure in the history of English art and literature." He also produced biographies and bibliographies of English writers such as Sir Thomas Browne, John Evelyn, Siegfried Sassoon, John Donne and Jane Austen. He was also a pioneer in the history of science, with studies of John Ray, William Harvey and Robert Hooke. His biography The Life of William Harvey was awarded the 1966 James Tait Black Memorial Prize. In 1967 he delivered the Wilkins Lecture at the Royal Society. Keynes was President of the Bibliographical Society (1952–1954) and was awarded the Society's Gold Medal in 1982.
His autobiography The Gates of Memory was published in 1981.
- A Bibliography of Dr. John Donne (1914, 1932, 1958, 1973)
- A Bibliography of William Blake (The Grolier Club, New York, 1921)
- Jane Austen: a Bibliography (Nonesuch Press, 1929)
- Selected Essays of William Hazlitt 1778 : 1830 (Nonesuch Press, 1930)
- The Works of Sir Thomas Browne: Miscellany Tracts, Repertorium, Miscellaneous Writings (Faber & Gwyer 1931)
- The Works of Thomas Browne: Letters (Faber & Faber, 1931)
- The Faber Gallery Series: Blake (Faber and Faber 1945)
- The Poetical Works of Rupert Brooke (Faber & Faber, 1946)
- Poetry and Prose of William Blake (Nonesuch 1948)
- Portraiture of William Harvey, London 1949. With a Catalogue and Reproductions of the Pictures. The Thomas Vicary Lecture 1948.
- The Personality of William Harvey, Cambridge University Press: 1949
- William Blake's Engravings, edited with an introduction (Faber and Faber, (1950)
- William Blake, 1757–1827 (1949) 1946 ? Blake (1953)
- The Tempera Paintings of William Blake (1951)
- The Apologie and Treatise of Ambroise Containing the Voyages Made Into Divers Places with Many of His Writings Upon Surgery (1951)
- Samuel Butler's Note-Books, selections (1951) with Brian Hill
- Poems of Rupert Brooke (1954)
- A Bibliography of Rupert Brooke (1954) Hart-Davis, The Soho Bibliographies, No.4)
- Harvey Though John Aubrey's Eyes (1958)
- A Bibliography of Dr. Robert Hooke (1960)
- Essays in Biography 1961 by J. M. Keynes, editor
- Dr. Timothie Bright 1550—1615. A Survey of his Life with a Bibliography of his Writings (1962)
- A Study of the Illuminated Books of William Blake: Poet, Printer, Prophet (1964)
- An Exhibition of the Illuminated Books of William Blake: Poet — Printer — Prophet (1964) with Lessing J. Rosenwald
- On Editing Blake (1964)
- Blake. The Masters 6 (1965)
- Blake: Complete Writings with Variant Readings, editor, Oxford University Press, 1966 (UK-Paperback, Revised). ISBN 0192810502
- William Blake. Songs of Innocence and of Experience, editor, with Introduction and Commentary. London: Oxford University Press (1967)
- Henry James in Cambridge (1967)
- Sir Thomas Browne, Selected Writings (1968)
- The Letters of Rupert Brooke (1968)
- William Blake Engraver (1969)
- Drawings of William Blake: 92 Pencil Studies. Selection, Introduction and Commentary, Dover Publications, Inc., New York, 1970 ISBN 0-486-22303-5
- William Blake's Water-Colours Illustrating the Poems of Thomas Gray (1972)
- Deaths Duell by John Donne (1973)
- The Marriage of Heaven and Hell (1975)
- The Gates of Memory (1981) Keynes, Geoffrey and Davidson, Peter (Eds.)
- A Watch of Nightingales (Stourton Press, 1981)
- Harriet Frances Keynes (1918–1918)
- Richard Darwin Keynes (1919–2010)
- Quentin George Keynes (1921–2003)
- William Milo Keynes (1924–2009)
- Stephen John Keynes (born 1927)
- Chapter Ii. History.amedd.army.mil. Retrieved on 2014-06-27.
- David McKitterick, ‘Keynes, Sir Geoffrey Langdon (1887–1982)’, rev. Stephen Lock, Oxford Dictionary of National Biography, Oxford University Press, 2004 accessed 18 February 2008.
- "The Bibliographical Society – Past Presidents". Bibsoc.org.uk. 2011-09-22. Retrieved 2012-08-17.
|Wikimedia Commons has media related to Geoffrey Keynes.|
- Geoffrey Keynes: The gates of memory. Oxford : Oxford University Press; ISBN 0-19-812657-3
- To Geoffrey Keynes: Articles from the "Book Collector" to Commemorate His Eighty-Fifth Birthday (The Book Collector, 1972, ISBN 0903482002) with Francis Meynell, A. N. L. Munby, David Garnett, John Sparrow