Sam Llewellyn was born on Tresco, Isles of Scilly, where his ancestors lived for many years. He grew up in Norfolk. Llewellyn went on to live in Toronto, Canada, and Ireland, before settling in Herefordshire, England, where he still lives now. Llewellyn has a deep love for the sea, and this has influenced much of his writing. He goes sailing regularly.
He was originally an editor and fine art dealer before becoming an author. He has become a prolific writer, and has written for both children and adults. He has also worked as a journalist with newspapers and magazines from both America and Britain.