John Andrew Boyle was born at Worcester Park in Surrey in 1916, to a family of Scottish origin. The family moved to Birmingham where Boyle's father, a versatile bibliophile and bookseller, became Bolivian consul and provided much of his early education. He taught him Latin and Greek and employed him in his bookshops in London and Birmingham, where he profited from wide reading that stood him in good stead for his later work and where he was attracted by a work in Persian. In 1933, Boyle won a scholarship to Birmingham University, where he graduated with first-class honours in German in 1936. He was then awarded an exchange studentship at Berlin, and there and at Göttingen he began the study of Oriental languages, under such scholars as H. H. Schaeder, Olaf Hansen and Richard Hartmann, giving him his first training in Old, Middle and New Persian, as well as Arabic and Turkish. It was in Professor Schaeder's Seminar in Berlin in the autumn of 1938 that Boyle first became acquainted with Tarikh-i Jahan-gusha (History of the World Conqueror) of Juvaini. With the threat of war Boyle returned to England in 1939 and became a postgraduate student at the School of Oriental and African Studies in London, with a Special Grant for Iranian studies and a Forlong Scholarship, but not for long – this was soon interrupted by the war.

In 1941 he became a sapper in the Royal Engineers, but the following year he was assigned to the Special Intelligence branch of the Foreign Office where he remained until 1950. In 1945 he married a colleague, Margaret Elizabeth Dunbar, who became a constant support in his work. He found time to continue his doctoral research, on Juvaini's History, which he completed in 1947 under the supervision of Vladimir Minorsky, who was the most important influence on Boyle's academic work, notable chiefly for his studies of the Mongol Empire. In 1949, Boyle wrote to the Trustees of the Gibb Memorial, asking if they would consider publishing his translation of volume one of Juvaini (the Persian text of which, of course, had been published by the Trust in 1912), but was told ‘that the Trustees saw no prospect of publishing this work’. A further request to publish his translation, in 1952, was ‘declined with thanks’, presumably on the grounds of limited resources.