Born at Eccles in Lancashire, Birley became a lecturer at Durham University in 1931, specialising in the archaeology of Hadrian's Wall. During World War II, he served in military intelligence. In 1949, he founded the Congress of Roman Frontier Studies and his many publications include Roman Britain and the Roman Army (1953).
Birley was professor of Romano-British History and Archaeology at Durham (1956-71) and became founder-chairman of the Vindolanda Trust. He was one of the directors of Durham University's training excavation at Corbridge and established in Durham a distinctive school of research into Roman Britain as a whole. Birley was the leading scholar of Roman-British studies in this country and his papers on military matters were brought together in 1988 as The Roman Army: Papers 1929-86. His final home was Carvoran, near his eldest son, Robin, director of the Vindolanda Trust.