John Jeffery Farnol was born in Aston, Birmingham, England, UK, son of Kate Jeffery and Henry John Farnol, a factory-employed brass-founded. The marriage were to have three more children, two boys and a girl. He brought up in London and Kent. He attended the Westminster Art School, after he had lost his job in a Birmingham metal-working firm. In 1900, he married Blanche Wilhelmina Victoria Hawley (1883-1955), the 16 years daughter of the noted New York scenic artist H. Hughson Hawley; they moved to the United States, where he found work as a scene painter. The marriage had a daughter, Gillian. He returned to England around 1910, and settled in Eastbourne, Sussex. In 1938, he divorced and remarried with Phyllis Mary Clarke on 20 May, and adopted her daugther, Charmian Jane. On 9 August 1952, he died after a long battle with cancer at 73 in Eastbourne.
He published his firt romance novel My Lady Caprice in 1907. The success of his early novels led Farnol to become a professional writer. He produced around 40 novels and volumes of stories, and some non-fiction and children's books. His last book was completed by his second wife Phyllis. Two of his early books, The Amateur Gentleman and The Broad Highway, have been issued in a version edited by mediatic romance novelist Barbara Cartland.