Frontman of the Dublin-born rock band The Coronas. The band founded their own independent record label called 3ú Records.
The Coronas formed in 2003, performing around Ireland until they signed to 3ú Records in 2006. The following year they released their debut album Heroes or Ghosts.
At the 2010 Meteor Awards, The Coronas beat out both Snow Patrol and U2 for the title of Best Irish Album.
He was born to record producer Joe O'Reilly and folk singer Mary Black. His brother is Conor and his sister, Roisin, is also a folk singer under the stage name Róisín O.
He previously dated MTV presenter Laura Whitmore. She was also featured in the Coronas' music video for "Mark My Words" in 2011.