Born in Merthyr Tydfil, Geinor attended the Royal Welsh College of Music and Drama and started her career teaching drama in California.
Geinor became Artistic Director of Theatr na nÓg in 1998 and since then has directed over 30 productions for the company. Her writing and direction reflect a warmth of character and love of storytelling, particularly of stories rooted in Wales. Her work for Theatr na nÓg has accumulated numerous awards over the years and been performed everywhere from Brazil to Hong Kong.