A native of Cappamore, County Limerick, Ireland, Piaras was born in 1962. He was ordained for the dioceses of Cashel and Emly and was curate in Rinn รณ gCuanach, Waterford, before studying religious education in Dublin and in New York. He worked widely in the catechetical field before joining the Society of Jesus in 2003. After his novitiate in Birmingham, he studied journalism in Dublin City University and worked in communications in the Irish province, most recently as editor of Sacred Space, the daily prayer site.