Mynors was educated at Summer Fields School, Oxford and won a scholarship to Eton, where he won the Newcastle Scholarship in 1922. At Eton and Balliol, he was a friend of Cyril Connolly. He was Hertford and Craven Scholar, and became a Fellow of Balliol in 1926. In 1944, he became Kennedy Professor of Latin at Cambridge University and in 1953 became Professor at Oxford.
He was a member of the Literary Committee for the New English Bible and worked on a new edition of Bede's Ecclesiastical History and various Latin translations. In 1963, he was knighted and in 1966 became president of the Classical Association. He was an expert on ancient church manuscripts. He was an honorary member of the American Academy of Arts and Sciences and the American Philosophical Society and received honorary degrees from many universities in Britain and at the University of Toronto.
Roger Mynors was killed in a car crash at the age of 86. "He had been working on his catalogue of the manuscripts in Hereford Cathedral Library, and was driving back to Treago, his country home at St Weonards near the Welsh border. As he left the cathedral he was heard to say that he had had a good day".
- R.A.B. Mynors, Cassiodori senatoris Institutiones, Oxford: Clarendon Press, 1937.
- R.A.B. Mynors, Durham cathedral MSS before 1200, 1939
- Bertram Colgrave and Sir Roger Mynors, Bedes Ecclesiastical history of the English People, Oxford: Clarendon Press, 1969.
- R.A.B. Mynors, C. Valerii Catulli Carmina, Oxford: Clarendon Press, OCT, 1958.
- R.A.B. Mynors, C. Plini Caecili Secundi, Epistularum libri decem, Oxford: Clarendon Press, OCT,1963
- R.A.B. Mynors, XII Panegyrici Latini, Oxford: Clarendon Press, OCT, 1964.
- R.A.B. Mynors, P. Vergili Maronis Opera, Oxford: Clarendon Press, OCT, 1969.
- R.A.B. Mynors (post.: with a pref. by R.G.M. Nisbet), Virgil Georgics, edited with a commentary by R.A.B. Mynors, Oxford: Clarendon Press, 1990.