Born and raised in Wicklow, Ireland, Ferdia began taking singing lessons at a very young age from his mother, a professional opera singer. He began competing at the age of seven and when he was 12, was cast in his first professional role in a tour of Ireland with Opera Theatre Company's production of Mozart's The Magic Flute. Ferdia then played the role of Miles in Benjamin Britten's opera based on the gothic ghost story novella Turn of the Screw, under conductor David Brophy.
When Ferdia was 14, his mother heard about an open call looking for a teenager to play the lead role in a musical movie called Sing Street. After waiting in line for eight hours, Ferdia managed to impress the casting people and received several callbacks, including one while he was on holiday in Spain with his family. He caught the next plane back and on his final audition, landed the role.
Ferdia turned 15 while filming and by the time the movie released, he was 16. He plays guitar and piano and gave an acoustic guitar performance when Sing Street premiered at the Sundance Film Festival.
Ferdia lives in Ireland with his parents, two older brothers Tadgh and Oisin, and younger sister Siofradh, as well as his black-and-white cat named Cosmo. In addition to playing music, Ferdia enjoys painting and poetry.