Born Karly Rose Greene in Belfast, Northern Ireland, on September 24th, 1987 to Stephen and Amanda Greene. She has two younger sisters, Louise and Lauren, who were more academically focused. Raised in Newtownabbey, she attended Monkstown Community School until the age of 16. Her stage credits include Sandy in the hit musical Grease and after this role, she joined Dealer's Agency, in Belfast where she was encouraged to attend a Summer Drama School with Centre Stage, run by Roma Tomelty and Colin Carnegie were she continued to enjoy theatre acting. At 15, she landed her first major role as Katie in the Oscar-nominated Everything in This Country Must (2004), a short film directed by Gary McKendry and based on the short story written by Colum McCann. Before this, the actress only worked on advertisements, and Billboards.