Byrne was born in Hampshire, and grew up amidst many artistic influences. She was raised in Stratford-upon-Avon, where the Royal Shakespeare Company is based. She would later tell an interviewer that her career in theatre design was predestined, and she began by studying architecture with the intention of building sets in theatre. She encountered costume design when studying theatre design with the English National Opera. She later said, "I worked in the theatre for quite a few years, doing costume and set design. In England, it's very much both." She also trained with the Motley Theatre Design Course.
