Kate was born in West Sussex. She was educated at Chichester High School and New College, Oxford. After graduating, she spent seven years in publishing. Her bestselling books have sold millions in over 40 countries.

Kate married old school friend Greg Mosse, after meeting him again twenty years later on a train by chance. Mosse lives with her husband and children, Martha and Felix, in West Sussex and Carcassonne.

In 1996 she published her first novel, Eskimo Kissing, about a young, adopted woman searching for her background. This was followed in 1998 by the thriller Crucifix Lane. From 1998 up to 2001, she held her post as the executive director of the Chichester Festival Theatre. Meanwhile she also remained engaged in research work for her up-coming novel. In 2005 she had international success with her novel, Labyrinth, an adventure story set both in the Middle Ages and the present.

She is the television presenter of the BBC Four literary chat show, Readers' and Writers' Roadshow and a well-known figure in the media. In 1996 she co-founded the annual Orange Prize for Fiction, of which she is also the Honorary Director. In 2000 she was named European Woman of Achievement for her contribution to the arts.

In 2006 Kate Mosse won a British Book Award for Labyrinth in the category "Richard & Judy's Best Read".

In October 2007 she released her novel, Sepulchre.

In February 2008 she appeared on the morality debate show, The Big Questions on BBC One.

In 2009 Kate contributed an essay to Modern Delight, a book inspired by J.B. Priestley's 1949 book Delight, published by Waterstone's to raise money for Dyslexia Action and the London Library.

In October 2009 she released her latest novel Winter Ghosts.

Kate currently presents the BBC Radio 4 programme A Good Read, inviting guests to discuss their favourite books.