Niamh is Irish. She went to UCD and got a BA in Italian and Politics. She worked in other areas, including fashion modelling, which eventually led her into acting.
She did stage and screen work in Ireland and then went to London and studied at RADA and also the Meisner Technique. She returned to Ireland where she played Nora Connolly on stage, directed by Frank Allen and the female lead in The Mad Man And The Nun. She now lives in London.