He has appeared in the films Snow White and the Huntsman (2012), Assassin's Creed (2016), and had regular roles in The Bisexual (2018), Resistance and Peaky Blinders (2019), Frank of Ireland (2021), and Bad Sisters (2022).

[3] Gleeson started acting in 2006, first appearing alongside his father in The Tiger's Tail directed by John Boorman, which was filmed the year he completed the Leaving Certificate.

Along with his father Brendan and brother Domhnall, Gleeson appeared in the Enda Walsh play The Walworth Farce in early 2015.

[1] He starred as Jimmy in the 2016 Irish drama series Rebellion, based on the 1916 Easter Rising.

[1] In 2019, Gleeson starred as Jimmy McCavern in Peaky Blinders, although criticized for his version of a Glaswegian accent, deemed acceptable due to his quality acting performance.