Caoimhín Ó Briain was born in 1986 in Dublin, Ireland. He studied cello and piano at the Royal Irish Academy of Music with cellist Aisling Drury-Byrne and pianist Hugh Tinney, achieving yearly scholarships. He has been awarded ARIAM Music teacher's diplomas in both piano and cello, and he currently studies with cellist William Butt at the RIAM.

Caoimhín has won all the major cello competitions at the Dublin Feis Ceoil. He has been a principle cellist and member of many orchestras over the last fifteen years including the National Youth Symphony Orchestra and Hibernian Orchestra. Regular orchestra and chamber music tours have taken him abroad to many countries, including a tour in the US with pianist John O'Conor.

Caoimhín played with BBC Wales Orchestra both in concert and for recording. In 2007 he performed Villa-Lobos with renowned Irish classical guitarist Redmond O'Toole. He has also performed in the National Concert Hall John Field Room with pianist Lance Coburn. He plays both traditional Irish and classical repertoire regularly with his his mother (harp) and brother (flute). He also performs on TV, Radio and in the studio with various bands, and his latest interests include Electronic music production.