Niall studied piano and composition at the Royal Irish Academy of Music. He was awarded first prize at the 1992 Dublin film festival's Music awards, chaired by English composer and critic Michael Nyman. Since then Niall has composed music for feature films, animation and many critically acclaimed and award-winning British television drama series including 'The Widower', 'Cilla' and 'Little Boy Blue'. He has received awards from the Irish Arts council, one of which included a series of seminars on film music by Ennio Morricone at the Chigiana Music school in Sienna.

Niall has received several IFTA (Irish Film & Television Awards) nominations and won the award for his score to the BBC film 'Loving Miss Hatto', starring Francesca Annis and Alfred Molina.

In 2017 he received the Venus award at the Badalona Film Festival in Barcelona for his score to the animated film 'The Lost Letter', narrated by Kate Winslet. In 2019, his score for the 26-part animation series 'Peek Zoo' was nominated for Best Score at the Irish Animation Awards.