Her parents were both heavily involved in amateur theatre, influencing Lisa toward studying drama, as well as being classically trained in both piano and singing.
She has played several leading roles, such as "Velma Kelly" in Chicago, "Florence" in Chess, "Laurey" in Oklahoma!, "Maria" in West Side Story and "Sandy" in Grease.
This led to her being cast in the American production of Riverdance – The Show as lead female vocalist in 2000, a position she held for five years while touring.
During this time, Kelly also met fellow vocalist Lynn Hilary, who would later go on to become a member of Celtic Woman in 2007 as a replacement for Méav Ní Mhaolchatha.
Kelly was again approached by Downes in 2004 and asked to be part of Celtic Woman, originally planned as a one-night event at Dublin's Helix Theatre.
Kelly performed "The Voice" in A New Journey, which was originally supposed to be sung by Méav Ní Mhaolchatha, and also features fiddler Máiréad Nesbitt.
On leaving Celtic Woman, Kelly told Charlie Patton of the Florida Times-Union, "It was an amazing experience, but with four kids, I just needed stability.
Kelly was one of four people involved who were connected to Celtic Woman – the others being violinist Máiréad Nesbitt, musical director and composer David Downes, and former member and vocalist Méav Ní Mhaolchatha.
Her family moved to Peachtree City, Georgia, US, where she announced the opening of The Lisa Kelly Voice Academy, indicating a switch from performing to teaching.