She was the daughter of Francesca Ashurst, and attended a variety of schools, including a state junior school in Barking, and a boarding school for eighteen months. During her teenage years she was involved in demonstrations against the Poll Tax, nuclear weapons and the first Gulf War. She studied for her A levels at Chelmsford College and achieved a First in a degree in Cultural Studies at the University of East London from 1992-1995.

Her first three novels feature Lily Pascale, an English literature lecturer who solves murder mysteries. Each of the succeeding novels is independent of the others.

Her literary agent is Simon Trewin at United Agents , and she is currently working upon her eighth novel.

In 2008 she was a member of the Edinburgh International Film Festival jury, along with Director Iain Softley and presided over by actor Danny Huston

She has taught English Literature at the University of Kent since 2004, and has previously taught at Dartmouth Community College, South East Essex College and the University of East London.

She reviews books for the Literary Review, the Independent on Sunday, and Scotland on Sunday.

Scarlett Thomas shares with Ariel, the protagonist in The End of Mr. Y, a wish to know everything:

"I'm very much someone who wants to work out the answers. I want to know what's outside the universe, what's at the end of time, and is there a God? But I think fiction's great for that--it's very close to philosophy."

Her new book, Our Tragic Universe, was published in May 2010 in the UK, and will be published in September 2010 in the USA. It was originally to be titled Death of the Author.

She is currently studying for an MSc in Ethnobotany, and working on her ninth novel, The Seed Collectors

In 2001 she was named by The Independent as one of 20 Best Young Writers.

In 2002 she won Best New Writer in the Elle Style Awards, and also featured as an author in New Puritans, a project led by the novelists Matt Thorne and Nicholas Blincoe consisting of both a manifesto and an anthology of short stories.