Gleeson formerly co-hosted The Weekly with Charlie Pickering alongside Judith Lucy and currently hosts Hard Quiz and Taskmaster Australia.

Gleeson was born in Gunnedah, New South Wales, and lived at nearby Tambar Springs[2] before boarding at St. Joseph's College, Hunters Hill, in Sydney.

[4] During his degree, Gleeson played the drums and occasionally sang vocals in an Australian band, The Fantastic Leslie, before leaving for a career in comedy.

In 2003 and 2004, Gleeson appeared in Network Ten's comedy sketch program skitHOUSE, playing various characters including the "Australian Fast Bowler", a parody of Dennis Lillee.

In 2015, Gleeson appeared on the ABC satirical television news program The Weekly with Charlie Pickering, hosting the segments "This Is What You Think", "Go Away" and "Hard Chat".