Liam is the youngest of the Clancy Brothers. He displayed an artistic disposition at an early age, while growing up in Carrick-on-Suir, Co. Tipperary. While still in his teens, Liam explored writing and painting, though he was particularly drawn to the theatre. Before he was twenty years old, Liam had founded the local dramatic society and had produced, directed, set-directed, and starred in "The Playboy of the Western World". Liam had also performed at the renowned Gaiety Theatre in Dublin.

In 1955,American song-collector Diane Hamilton arrived at the Clancy home while on a song-collecting tour of Ireland. Liam joined her on the trip to Keady, Co. Armagh, where they met the singer Sarah Makem and her son, Tommy. Both Liam and Tommy emigrated to America the following year, pursuing careers in acting, both on stage and television.

Liam began singing with his brothers at fund-raising events for the Cherry Lane Theatre and the Guthrie benefits. The Clancy Brothers & Tommy Makem, began recording on Paddy Clancy's "Tradition" label in the late 50's. A record breaking 16 minute long performance on the Ed Sullivan Show launched the group into stardom. The quartet recorded numerous albums for Columbia Records and enjoyed great success during the 60's folk revival.

In 1973, Liam left the group to pursue a solo career. Hewas based in Calgary, where he became an established television performer. Liam had his own series, which won a Canadian Emmy Award. A few years later, Liam teamed up again with his old pal Tommy Makem. As Makem & Clancy, the two recorded several hits including "The Band Played Waltzing Matilda" and "The Dutchman". They toured and recorded together until the late 80's.

Liam joined his brothers and nephew Robbie O'Connell in 1990, though he still performed some shows with his Fairweather Band as well as with the Phil Coulter Orchestra. From 1996-1999, Liam toured with his son, Donal Clancy, and Robbie O'Connell. The group, known as Clancy, O'Connell, & Clancy, delighted audiences across North America and Europe. They released two highly praised albums together.

Liam currently performs as a solo act at pubs, theatres, and festivals across North America and Ireland. He is also completing work on his autobiography. Liam also runs his own recording studio at his estate in Ring, Co. Waterford.