[8] He completed his secondary education as a boarding student at St Jarlath's College in Tuam.

[11] He went on to train at the Stella Adler Studio of Acting in New York and Bow Street Academy in Dublin.

[12][13] In 2006, Ó Héalai made his onscreen debut as a teenager in the recurring role of Jeaic in season 1 of the TG4 coming-of-age family series Aifric.

Ó Héalai played Otis in the 2019 American psychological thriller Impossible Monsters.

Ó Héalaí stars as John Cunliffe in the Irish-language film Foscadh, an adaptation of the social novel The Thing About December by Donal Ryan.