Joanne McCarthy was born and raised on the Central Coast of NSW, the eldest of 11 children. She attended Catholic and public schools and started nursing training at Royal Prince Alfred Hospital in Sydney. She became the Gosford Star newspaper's first cadet journalist in 1980, and eventually worked for the Central Coast Express Advocate until 2002 – when she joined the Newcastle Herald.
From 2006 she started writing about child sexual abuse in institutions, primarily the Catholic Church. She won the Graham Perkin Award for Journalist of the Year in 2012, the Gold Kennedy Award for NSW Journalist of the Year in 2013, the Gold Walkley Award in 2013, and the Sir Owen Dixon Chambers Law Reporting of the Year Award in 2013 for her writing on institutional child sex and campaign for a royal commission – which contributed to the establishment of the Royal Commission into Institutional Responses to Child Sexual Abuse.
She has three adult sons, a dog and a cat. She enjoys running, reading, bushwalking and travelling, and hates cooking.