John Turton Randall was born on 23 March 1905. He was educated at Manchester University. He married Doris Duckworth in 1928, with whom he had one son.

He began his career as a physics researcher at the General Electric Company Ltd (GEC), 1926-37. He was Warren Research Fellow of the Royal Society, 1937-43, and an honorary member of staff of Birmingham University, 1940-3. He carried out research on behalf of the Admiralty, 1939-43, and, with Henry Boot, discovered the cavity magnetron, which was central to the development of shortwave radar. He was a Lecturer in the Cavendish Laboratory, Cambridge University, 1943-4; Professor of Natural Philosophy, St Andrew's University, 1944-6; and Wheatstone Professor of Physics, 1946-61, and Professor of Biophysics, 1961-70, King's College, London. He was the first Director of the MRC Biophysics Research Unit (later the Randall Centre), King's College, London, 1947-70, where pioneering research into the structure of DNA was undertaken. He also served as Chairman of the School of Biological Sciences, King's College, London, 1963-9. He retired in Edinburgh, 1970, and continued to pursue research projects in the Zoology Department, Edinburgh University. He died on 16 June 1984.

He was awarded a knighthood, 1962. He was an Honorary Professor, Edinburgh University, and an Emeritus Professor of Biophysics, King's College, London.

His publications include: editor, "The Diffraction of X-rays by Amorphous Solids, Liquids and Gases" (1934); editor, "Nature and Structure of Collagen" (1953); and joint editor, "Progress in Biophysics and Biophysical Chemistry" (1950-5).