Greene was born in Cork, Ireland.
She became interested in acting when she saw Red Riding Hood along with her parents at the Opera House in Cork. A short time later she joined the CADA Performing Arts in Cork, where she took part in theatre plays and musicals until she was 19 years old. When Greene was six years old she first appeared on stage. She played a twin in the theatre play The King and I at the Opera House in Cork. After leaving CADA Performing Arts she was trained at the Gaiety School of Acting in Dublin, from which she graduated in 2006.
