Diarmuid is an actor, writer and dialogue coach. Film: Recent work includes the new release, The Watchers (2024), Foscadh (2022), Finky (2020), Black '47 (2018) and Pilgrimage (2017).

Two new feature films are in post production: Bring Them Down and Froggie. TV: Diarmuid was nominated for an IFTA for his lead role in Corp+Anam Series 1+2 (TG4), narrated An Bhoirinn (TG4) which won the Oireachtas Best Television Series and wrote and performed 'Pádraic Ó Conaire' which won Best Feature Documentary at the Celtic Media Festival. Other series work includes FBI International (CBS), Der Irland Krimi (ARD), Ros na Rún and Rásaí na Gaillimhe (TG4), Scúp and Custer's Last Stand Up (BBC NI), Machair (STV) and Ecu! Ecu!, Eureka! and Thou Shalt Not Kill (RTÉ).