Cahill grew up in a musical household in Mullingar, County Westmeath, in Ireland. At the age of four, his father provided him with music lessons, leading to a five-year "Schola Cantorum" music scholarship at his local secondary school. Undergoing formal classical training at the Royal Irish Academy of Music, he was a multiple prize winner in various competitions across Ireland, including the RIAM "Promising Young Singer of 2010" and the "John McCormack Young Tenor Award". Cahill auditioned for and won a spot with Celtic Thunder, replacing original member Paul Byrom. His voice has been featured on the albums Heritage, Storm, Voyage, Voyage II, and Mythology, as well a pair of Christmas albums. In 2013 he was voted Tenor of the Year by The Irish Music Association in the United States in recognition of his stage performances.
The following January, Cahill announced he was leaving the group for a solo career, but returned for an Australian tour in March after vocalist and original member George Donaldson died of a heart attack. After leaving again, he once more rejoined the group in December 2015 after Colm Keegan's departure. In the winter of 2017, Emmet Cahill's Ireland appeared under the Celtic Thunder banner; in March it entered the World Music albums chart at number one. ~ Thom Jurek, Rovi