| 'But what about the earlier city?' John Rocque's Exact Survey (1756) as a source for medieval Dublin | Montague, John | Article in Book | Four Courts Press | 2013 |
| 'The western world's tower of honour and dignity' : the career of Muirchertach Ua Briain in context | Duffy, Seán | Article in Book | | 2006 |
| 1169 and all that | Duffy, Seán | Article in Journal | | 2019 |
| 850 years of oppression? An introduction to this speciaL issue marking the 850th anniversary of the Anglo-Norman ('recte' English?) invasion of Irerland | Duffy, Seán | Article in Journal | | 2019 |
| A dead man at Ballyshannon | Woolf, Alex, 1963- | Article in Book | Four Courts Press | 2007 |
| A deserted medieval village at Ballysheehan, Co. Tipperary | Duffy, SeánO'Donovan, Edmond | Article in Journal | | 2002 |
| Antiquarianism and the Gaelic revival in county Louth in the pre-famine era | Duffy, Seán | Article in Journal | | 1988 |
| Art Murphy and Gaelic literary activity in the Dundalk area in the 1820s | Duffy, Seán | Article in Journal | | 1987 |
| Atlas of Irish history | Duffy, Seán | Monograph or Collective Volume | Gill & Macmillan | 2000 |
| Atlas of Irish history | | Monograph or Collective Volume | Gill & Macmillan | 1997 |
| Brian Boru : imperator scotorum | Duffy, Séan | Article in Journal | | 2014 |
| Brian Boru and the Battle of Clontarf | Duffy, Seán | Monograph or Collective Volume | Gill & Macmillan | 2013 |
| Cambridge History of Ireland, vol 1: 600-1550; [edited by] Brendan Smith. Cambridge, 2018. Reviewed by Seán Duffy | Duffy, Seán | Article in Journal | | 2018 |
| Carlingford Castle in the Middle Ages | Duffy, Seán | Article in Journal | | 2023 |
| Dublin Castle : From Fortress to Palace. Volume 1: Vikings to Victorians. A history of Dublin Castle to 1850. | Duffy, Seán ; Montague, John ; Mulligan, Kevin ; O'Neill, Michael | Monograph or Collective Volume | National Monuments Service | 2022 |
| Emerging from the mist : Ireland and Man in the eleventh century | Duffy, Seán | Article in Book | | 2002 |
| Gerald of Windsor and the origins of the Geraldines | Duffy, Seán | Article in Book | | 2016 |
| Historical revisit : Goddard Henry Orpen, Ireland under the Normans, 1169-1333 (1911-20) | Duffy, Seán | Article in Journal | | 2000 |
| Ireland and Scotland : nation, region, identity; náisiún, régiún, céannacht; nàisean, ceàrn tìre, fèineachd : a record of the inter-disciplinary conference held in Trinity College Dublin and the Irish Film Centre 29-30 September 2000 | | Monograph or Collective Volume | Centre for Irish-Scottish Studies, TCD for the Irish-Scottish Academic Initiative | 2001 |
| Ireland and Scotland, 1014-1169 : contacts and caveats | Duffy, Seán | Article in Book | | 2000 |
| Ireland and the Irish Sea region, 1014-1318 | Duffy, Seán | Thesis | | 1993 |
| Ireland and the middle ages | Duffy, Seán | Monograph or Collective Volume | [s.n.] | 1997 |
| Ireland in the middle ages | Duffy, Seán | Monograph or Collective Volume | Macmillan | 1997 |
| Ireland under the Normans, 1169-1333 | Duffy, SeánOrpen, G. H. (Goddard Henry) | Monograph or Collective Volume | Four Courts | 2005 |
| Ireland's Hastings : the Anglo-Norman conquest of Dublin | Duffy, Seán | Article in Journal | | 1998 |
| Ireland, c.1000–c.1100 | Duffy, Seán | Article in Book | | 2009 |
| Irish and Welsh responses to the Plantagenet Empire in the reign of Edward I | Duffy, Seán | Article in Book | | 2016 |
| Irishmen and Islesmen in the kingdoms of Dublin and Man, 1052-1171 | Duffy, Seán | Article in Journal | | 1992 |
| John and Ireland : the origins of England's Irish problem | Duffy, Seán | Article in Book | | 1999 |
| King John’s expedition to Ireland, 1210 : the evidence reconsidered | Duffy, Seán | Article in Journal | | 1996 |
| Let sleeping dogs lie | Duffy, Seán | Article in Journal | | 2009 |
| Medieval Dublin I: proceedings of the Friends of Medieval Dublin symposium 1999 | Duffy, Seán | Monograph or Collective Volume | Four Courts | 2000 |
| Medieval Dublin II : proceedings of the Friends of Medieval Dublin Symposium 2000 | | Monograph or Collective Volume | Four Courts | 2001 |
| Medieval Dublin III : proceedings of the Friends of Medieval Dublin Symposium 2001 | | Monograph or Collective Volume | Four Courts | 2002 |
| Medieval Dublin IV : proceedings of the Friends of Medieval Dublin Symposium | | Monograph or Collective Volume | Four Courts | 2003 |
| Medieval Dublin IX : proceedings of the Friends of Medieval Dublin symposium, 2007 | | Monograph or Collective Volume | Four Courts | 2009 |
| Medieval Dublin V : proceedings of the Friends of Medieval Dublin Symposium, 2003 | | Monograph or Collective Volume | Four Courts | 2004 |
| Medieval Dublin VI : proceedings of the Friends of Medieval Dublin Symposium 2004 | | Monograph or Collective Volume | Four Courts | 2005 |
| Medieval Dublin VII : proceedings of the Friends of medieval Dublin symposium 2005 | | Monograph or Collective Volume | Four Courts | 2006 |
| Medieval Dublin VIII : proceedings of the Friends of Medieval Dublin Symposium 2006 | | Monograph or Collective Volume | Four Courts | 2008 |
| Medieval Dublin X : proceedings of the Friends of Medieval Dublin symposium, 2008 | | Monograph or Collective Volume | Four Courts | 2010 |
| Medieval Dublin XI : proceedings of the Friends of Medieval Dublin symposium, 2009 | | Monograph or Collective Volume | Four Courts | 2011 |
| Medieval Dublin XII : proceedings of the Friends of Medieval Dublin symposium, 2010 | | Monograph or Collective Volume | Four Courts | 2012 |
| Medieval Dublin XIII : proceedings of the Friends of Medieval Dublin symposium, 2011 | | Monograph or Collective Volume | Four Courts | 2013 |
| Medieval Dublin XIV : proceedings of the Friends of Medieval Dublin symposium, 2012 | | Monograph or Collective Volume | Four Courts | 2015 |
| Medieval Dublin XIX : proceedings of the Friends of Medieval Dublin Symposia | NA | Monograph or Collective Volume | Four Courts Press | 2023 |
| Medieval Dublin XV : Proceedings of the Friends of Medieval Dublin symposium, 2013 | | Monograph or Collective Volume | Four Courts | 2016 |
| Medieval Dublin XVI : Proceedings of Clontarf 1014–2014: national conference marking the millennium of the Battle of Clontarf | | Monograph or Collective Volume | Four Courts Press | 2017 |
| Medieval Dublin XVII | | Monograph or Collective Volume | Four Courts | 2019 |
| Medieval Dublin XVIII | | Monograph or Collective Volume | Four Courts | 2020 |
| Medieval Dublin XX | Duffy, Seán | Monograph or Collective Volume | Four Courts Press | 2025 |
| Medieval Ireland : an encyclopedia | | Monograph or Collective Volume | Routledge | 2005 |
| Medieval Scotland & Ireland : overcoming the amnesia | Duffy, Seán | Article in Journal | | 1999 |
| Nicholas O'Kearney : the last of the bards of Louth | Duffy, Seán | Monograph or Collective Volume | Cuchulainn Press | 1989 |
| Obituary. James Francis Lydon (1928-2013) | Duffy, Seán | Article in Journal | | 2014 |
| Origins | Duffy, Seán | Article in Book | | 1997 |
| Origins | Duffy, Seán | Article in Book | | 2000 |
| Ostmen, Irish and Welsh in the eleventh century | Duffy, Seán | Article in Journal | | 1995 |
| Pre-Norman Dublin : capital of Ireland? | Duffy, Seán | Article in Journal | | 1993 |
| Princes, prelates and poets in medieval Ireland : essays in honour of Katharine Simms | | Monograph or Collective Volume | Four Courts | 2013 |
| Relations between Ostmen, Irish and Welsh in the eleventh century | Duffy, Seán | Article in Journal | | 1995 |
| Robert the Bruce's Irish wars : the invasions of Ireland 1306-1329 | | Monograph or Collective Volume | Tempus | 2002 |
| See Rome and die : the burial-place of Donnchad Mac Briain | Duffy, Séan | Article in Journal | | 2014 |
| The "Continuation" of Nicholas Trevet : a new source for the Bruce invasion | Duffy, Seán | Article in Journal | | 1991 |
| The 1169 invasion as a turning-point in Irish-Welsh relations | Duffy, Seán | Article in Book | | 1999 |
| The British perspective | Duffy, Seán | Article in Book | | 2003 |
| The Bruce brothers and the Irish sea-world, 1306-29 | Duffy, Seán | Article in Journal | | 1991 |
| The Bruce invasion of Ireland : a revised itinerary and chronology | Duffy, Seán | Article in Book | | 2002 |
| The English Isles : cultural transmission and political conflict in Britain and Ireland, 1100-1500 | | Monograph or Collective Volume | Four Courts | 2013 |
| The first Ulster plantation : John de Courcy and the men of Cumbria | Duffy, Seán | Article in Book | | 1995 |
| The Gaelic account of the Bruce invasion, Cath Fhochairte Brighite : medieval romance or modern forgery? | Duffy, Seán | Article in Journal | | 1988 |
| The Geraldines and medieval Ireland : the making of a myth | | Monograph or Collective Volume | Four Courts Press | 2016 |
| The hermits of St Augustine in medieval Dublin : their history and archaeology | Duffy, Sean,Simpson, Linzi, | Article in Book | | 2009 |
| The lords of Galloway, earls of Carrick, and the Bissetts of the Glens : Scottish settlement in thirteenth century Ulster | Duffy, Seán | Article in Book | | 2004 |
| The Loughross Gaelic scholar, Dr James Woods | Duffy, Seán | Article in Journal | | 1989 |
| The problem of degeneracy | Duffy, Seán | Article in Book | | 1997 |
| The royal dynasties of Dublin and the Isles in the eleventh century | Duffy, Seán | Article in Book | | 2006 |
| The saint's tale | Duffy, Seán | Article in Book | | 2014 |
| The Turnberry Band | Duffy, Seán | Article in Book | | 2013 |
| The Welsh conquest of Ireland | Duffy, Seán | Article in Book | | 2015 |
| Town and Crown : The Kings of England and their City of Dublin | Duffy, Seán | Article in Book | | 2005 |
| Ulster and the Irish sea region in the twelfth century | Duffy, Seán | Article in Journal | | 1996 |
| What happened at the Battle of Clontarf? | Duffy, Séan | Article in Journal | | 2014 |
| ‘A real Irish historian’. Seán Duffy talks to James Lydon who last year retired as Lecky Professor of Modern History in Trinity College, Dublin | Duffy, Seán | Article in Journal | | 1995 |