McGlynn was born in Dublin and attended Coláiste na Rinne and Blackrock College. He was a student of Music and English at University College Dublin and Trinity College where he studied for an M.Litt degree. He was a member of the RTÉ Chamber Choir and in 1987 he founded the Irish choral group Anúna (originally spelt "An Uaíthne"). Anúna have released fourteen albums, almost exclusively featuring his arrangements and original works. "Deep Dead Blue" was nominated for a Classical Brit Award in 2000 and went Top 5 in the UK Classical Charts. "Anúna: Celtic Origins" was the biggest selling world music CD in the US in August 2007 according to Nielsen Soundscan [https://archive.is/20070714202052/http://www.elevationgrp.com/anuna/media_07.html], and remained in the top twenty albums of the Billboard World Music Charts until early 2008. Although best known as a writer of choral music, McGlynn has written orchestral and instrumental works as well as cantatas and masses. 2007 saw the premiere of the cantata "St. Francis" commissioned by RTÉ, the Irish National broadcasting station. It is a setting of texts associated with Francis of Assisi for tenor, choir and symphony orchestra. The album "Behind the Closed Eye" is a collaboration with the Ulster Orchestra, Northern Ireland's premiere orchestra.