Born in Geraldton, Kate Mulvany's childhood was interspersed with frequent hospital visits to Perth due to a form of kidney cancer, Wilms' tumour. Back in Geraldton, she mixed happily with the close-knit Sicilian community that resided in the town.
Mulvany graduated from Curtin University in 1997. She began her theatre career in Perth and later moved to Sydney where she worked with the Sydney Theatre Company, Company B Belvoir and Pork Chop Productions. She has also been writer-in-residence at the Naked Theatre Company, Sydney.
In 2007, Mulvany was nominated in the Best Actress in a Lead Role category in the Sydney Theatre Awards for her performance in her play, The Seed. In 2011, Mulvany adapted and acted in the Bell Shakespeare production of Julius Caesar.
In 2019, Sydney Theatre Company produced Mulvany's new version of Friedrich Schiller's Mary Stuart, with Caroline Brazier as Mary Stuart and Helen Thomson as Elizabeth Tudor.