Hannon wrote the theme tunes for the television sitcoms Father Ted and The IT Crowd, as well as the original songs for the musical film Wonka (2023).

For the same episode, Hannon wrote "The Miracle Is Mine", the 'typical' Eurovision ballad sung by Ted's nemesis, Father Dick Byrne.

A dream sequence in the episode shows Ted and Dougal in the song's pop video, with Hannon providing vocals.

This was in order to attempt to exploit the new UK Singles Chart download rules, and get the song featured in the Top 40 releases.

[7] The same year, Hannon sang and wrote the lyrics for the song "Somewhere Between Waking and Sleeping" on the Air album Pocket Symphony, released in the United States on 6 March 2007.

[citation needed] When the band Keane played at the O2 Arena in London that July, "A Bad Dream" was introduced by Hannon, who read the poem "An Irish Airman Foresees His Death" by W. B. Yeats, upon which the song is based.

[10] In 2009, Hannon collaborated with Thomas Walsh from the Irish band Pugwash to create a cricket-themed pop album, under the name the Duckworth Lewis Method.

Hannon composed the music for a stage adaptation of Arthur Ransome's novel Swallows and Amazons (1930), which premiered in December 2010 at the Bristol Old Vic, with book and lyrics by Helen Edmundson.

[16] Hannon's second opera for which he composed the music, In May (with book by Frank Alva Buecheler and English translations by Tim Clarke), premiered at Lancaster University's Nuffield Theatre[17] in May 2013.

[22][23][24] With Davey, Hannon is a patron of the Irish animal charity My Lovely Horse Rescue, named after the Father Ted Eurovision song for which he wrote the music.