He is also known for his leading roles in films such as The General (1998), In Bruges (2008), The Secret of Kells (2009), The Guard (2011), Calvary (2014), Frankie (2019), and The Banshees of Inisherin (2022) for which he received a nomination for the Academy Award for Best Supporting Actor.

[3] He received his second-level education at St Joseph's CBS in Fairview, Dublin where he was a member of the school drama group.

After training as an actor, he worked for several years as a secondary school teacher of Irish and English at the now defunct Catholic Belcamp College in north County Dublin, which closed in 2004.

In an NPR interview to promote Calvary in 2014, Gleeson stated he was molested as a child by a Christian Brother in primary school but was in "no way traumatised by the incident.

[8] Among his other Dublin theatre work are Patrick Süskind's one-man play The Double Bass and John B. Keane's The Year of the Hiker.

[9] He first came to prominence in Ireland for his role as Michael Collins in The Treaty, a television film broadcast on RTÉ One, and for which he won a Jacob's Award in 1992.

He has acted in such films as Braveheart, I Went Down, Michael Collins, Gangs of New York, Cold Mountain, 28 Days Later, Troy, Kingdom of Heaven, Lake Placid, A.I.

He won critical acclaim for his performance as Irish gangster Martin Cahill in John Boorman's 1998 film The General.

In his review of In Bruges, Roger Ebert described the elder Gleeson as having a "noble shambles of a face and the heft of a boxer gone to seed.

[14] In 2016, he appeared in the video game adaptation Assassin's Creed and Ben Affleck's crime drama Live by Night.

[3] He played the fiddle during his roles in Cold Mountain, Michael Collins, The Grand Seduction, and The Banshees of Inisherin, and also features on Altan's 2009 live album.