Laoise O’Brien performs a vast repertoire spanning a thousand years. She has worked as a chamber musician, orchestral player and a solo artist in multiple genres from medieval, renaissance, baroque through to newly-composed works. In addition to instrumental settings, she has performed in productions of opera, oratorio, musicals, theatre pieces, dance, drama and bespoke programmes for young people.

As a soloist, Laoise has performed with the RTÉ Concert Orchestra, Irish Chamber Orchestra, Camerata Kilkenny and the Irish Baroque Orchestra under directors, Monica Huggett, Elizabeth Wallfisch, Nicholas Kraemer and Maya Homburger. She has also performed with many ensembles including Resurgam, Sestina, The Gregory Walkers, the Irish Consort and the National Symphony Orchestra of Ireland.

Laoise has been involved in the design and delivery of programmes for Kilkenny Arts Festival, Galway Early Music Festival, East Cork Early Music Festival, Sligo Baroque Festival, Ardee Baroque Festival, Killaloe Chamber Music Festival, MusicTown, The Ark Children's Cultural Centre, Culture Night, Music Network, Music Generation, TU Dublin, The Office of Public Works, The Heritage Council, and RTÉ where she is regularly invited to contribute to radio broadcasts.