Whitby was born in February 1952,^[1] to Joan and Gordon Whitby, a physician and biochemist.^[2] He read Literae Humaniores at Corpus Christi College, University of Oxford.^[3] He then spent three years working as a civil servant in the Scottish Office. He returned to Oxford to conduct postgraduate study in Byzantine history.^[4] He completed his Doctor of Philosophy (DPhil) degree in 1981 with a doctoral thesis titled "The Historiae of Theophylact Simocatta".^[5]

Whitby held a junior research fellowship at Merton College, Oxford.^[6] In 1987, he joined the Ancient History department at the University of St Andrews. He became head of department in 1993 and received a personal chair in 1995 as Professor of Ancient History.^[4]

He was Professor of Classics and Ancient History at the University of Warwick,^[7] having joined the Department of Classics and Ancient History in 1996.^[8] He also served as pro-vice-chancellor 'Teaching, Learning and Quality' from 2003,^[9] and then 'Academic Planning and Resources'.^[3]

On 1 September 2010, he became pro-vice-chancellor and head of College of Arts and Law at the University of Birmingham.^[3]

In 2007, Whitby was awarded a Doctor of Letters (DLitt) honorary degree by the University of Warwick.^[10] He received one of the 2009 Distinguished Book Awards from the Society for Military History for The Cambridge History of Greek and Roman Warfare.^[11]

• The Emperor Maurice and his Historian: Theophylact Simocatta on Persian and Balkan Warfare (1988).
• Chronicon Paschale 284–628 AD (1989), with Mary Whitby.
• The Cambridge Ancient History XIV; AD 425–600 (2000), co-editor.
• Rome at War AD 293–696 (2002).
• The Cambridge History of Ancient Warfare (2005), co-editor.
• Christian Persecution, Martyrdom and Orthodoxy (2006).
• Sparta. New York: Routledge (2002).