[8] As a young man Hannigan began performing at festivals and local events, playing the uilleann pipes, tin whistle and percussion instruments.
[11] Hannigan opened Oisin Studios in Milton Keynes, England, and produced a number of albums,[12] including Tig (Serious Kitchen),[13] and Not to Scale (Kerfuffle).
In 2001 Hannigan arranged and performed all the instrumental solo parts for the Lionhead video game Black and White composed by Russell Shaw.
In 2008, after moving to Canada, Hannigan and Tomkins formed a band called Cairdeas (Friends) with singer Elizabeth Barlow, and independently released an album of Irish songs and tunes, Generous Lover.
[23] In 2011 Hannigan performed The Brendan Voyage, by Shaun Davey, the only classical suite written especially for uilleann pipes, accompanied by the Northumberland Orchestra in Cobourg.
Hannigan was the sound editor and audio effects creator for the 26 part animated film series Legend of Ponnivala, released in 2013.