Born in 1949, he was educated at Eton College, where he was a scholar, at Jesus College, Cambridge, where he took first-class honours in 1969, and at Balliol College, Oxford, where he took first-class honours in Literae Humaniores in 1971 (BA and hence subsequently MA) and a DPhil in 1978 with a thesis entitled Maussollos of Karia.
In 1971 he was elected to a Prize Fellowship of All Souls College, which he held until 1977. Then from 1978 until 1997, he was University Lecturer in Ancient History in the University of Oxford and Fellow and Tutor in Classics at Oriel College, Oxford, including one year, 1994/95, in which he was a member of the Institute for Advanced Study in Princeton, New Jersey. He moved to University College London, where in 1998 he was appointed Professor of Classics and Ancient History. In 2006 he was promoted with the title Grote Professor of Ancient History, retaining the title Professor of Classics.
He was elected a Fellow of the British Academy in 2004.
Hornblower was elected Senior Research Fellow of All Souls College, Oxford, taking up his appointment in Michaelmas Term 2010. At the same time, the Recognition of Distinction Committee conferred upon him the title Professor of Classics and Ancient History.
His current interest is classical Greek historiography (especially Herodotus and Thucydides) and the relation between historical texts as literature and as history. He has published an historical and literary commentary on Thucydides in three volumes (Oxford University Press, 1991, 1996, 2008). His latest sole-authored book is Thucydides and Pindar: Historical Narrative and the World of Epinikian Poetry (Oxford University Press, 2004). He is also co-editor, with Professor Catherine Morgan of King's College London, of Pindar's Poetry, Patrons, and Festivals: From Archaic Greece to the Roman Empire (OUP, 2007), a collection of papers by experts on historical, literary, archaeological and anthropological aspects of Pindar and his world.
Since 1979 he has been involved with the Lexicon of Greek Personal Names and co-edited Greek Personal Names: Their Value as Evidence (Oxford University Press, 2000).
In 1996 he co-edited the third and most recent edition of the Oxford Classical Dictionary.
- Hornblower, Simon (1982), Mausolus, Clarendon Press, ISBN 978-0-19-814844-9
- Hornblower, Simon; Greenstock, M C (1984), The Athenian empire, London Association of Classical Teachers, ISBN 978-0-903625-17-3
- Hornblower, Simon (1983), The Greek world, 479-323 BC, London, ISBN 978-0-416-75000-3
- Hornblower, Simon (1987), Thucydides, Johns Hopkins University Press, ISBN 978-0-8018-3529-2
- Hornblower, Simon (1994), Greek historiography, Clarendon Press, ISBN 978-0-19-814931-6
- Hornblower, Simon; Spawforth, Antony (1996), The Oxford classical dictionary, Oxford, ISBN 978-0-19-268767-8
- Hornblower, Simon; Spawforth, Antony (2000), Who's who in the classical world, Oxford University Press, ISBN 978-0-19-280107-4
- Burn, A R; Walbank, F W; Hornblower, Simon (2002), The Folio history of Ancient Greece, Folio Society, OCLC 50578593
- Hornblower, Simon (2004), Thucydides and Pindar : historical narrative and the world of Epinikian poetry, Oxford, ISBN 978-0-19-924919-0
- Hornblower, Simon; Morgan, Catherine (2007), Pindar's poetry, patrons, and festivals : from archaic Greece to the Roman Empire, Oxford, ISBN 0-19-929672-3