In 1964, Norwich left the diplomatic service to become a writer. His subsequent books included histories of Sicily under the Normans (1967, 1970), Venice (1977, 1981), Byzantium (1988, 1992, 1995), the Mediterranean (2006), and the Papacy (2011), amongst others (see list below). He also served as editor of series such as "Great Architecture of the World", "The Italian World", "The New Shell Guides to Great Britain", "The Oxford Illustrated Encyclopaedia of Art" and the "Duff Cooper Diaries".