From Feeny, County Derry, Northern Ireland, Tiernagh began dancing at the age of a six with the McCaul Academy. Her love for dance grew continuously, winning many major titles including the All Ireland Championships and runner up at the World Championships. Tiernagh graduated with a first class honours degree in Personalised Medicine while pursuing her dream of performing professionally. In January 2025, she joined the cast of Riverdance and was honoured to perform the female lead role in April 2025. Tiernagh describes the moment as surreal and is forever grateful for the amazing opportunity to share her passion and love for dance. She credits her incredible, supportive family for helping her achieve these dreams and is excited for the future ahead with Riverdance.