He is best known for his roles in the RTÉ One drama Love/Hate (2010–2011) and the Channel 4 sitcoms London Irish (2013) and Derry Girls (2018–2022).
[2] Upon graduation from Guildhall, Campion played Galanba in the Royal National Theatre production of The White Guard.
[9] In 2017, he appeared in the EastEnders limited spinoff Kat & Alfie: Redwater and the horror film The Cured.
[10] In 2018, Campion began playing the guest role of Father Peter in the Channel 4 sitcom Derry Girls.
Campion played Henry Vickers in the Acorn TV crime drama Dead Still[13] and the teacher Sweeney in the coming-of-age film Dating Amber in 2020, and the Roman consul Libo in the Sky Atlantic series Domina in 2021.