[1] Gleeson has performed in many musicals and plays in Australia and in London's West End including Mamma Mia!, Eureka, The Far Pavilions, and Imagine This.

[citation needed] In the United Kingdom he has performed in plays at The Royal National Theatre and in the West End of London.

He has appeared in the popular BBC soap opera EastEnders, playing SJ Fletcher's boyfriend Sid Clarke.

[citation needed] In August 2012, he played Anatoly Sergievsky in an Australian production of Chess.

[4] From 2014 Gleeson played Jean Valjean in the Australian tour of Cameron Macintosh's Les Miserables.

From December 2016 to June 2017, he played Valjean in the West End production of Les Misérables.