Caryl Lewis came to prominence as an author with Martha, Jac a Sianco (Y Lolfa), which won the Wales Book of the Year award in 2005. In 2007 Parthian published Gwen Davies's English translation of the novel. In 2009 a film adaptation by the author of the novel was released.
Caryl Lewis has written widely for television, the stage, and for children. Her first novel, Iawn, boi? (OK, boyo?, Y Lolfa 2003), for teenagers, won the Tir na n-Og prize in 2004. She is the author of the popular children‘s book series, Y Teulu Boncyrs (The Bonkers Family, Y Lolfa) while her story book, illustrated by Valeriane Leblond, Sgleinio’r Lleuad (Polishing the Moon) was published by Y Lolfa in 2014.
Y Gemydd (The Jeweller, Y Lolfa 2007) was shortlisted for the Wales Book of the Year award in 2008 as was her novel Naw Mis (Nine Months, Y Lolfa 2009). Her collection of short stories, Plu (Feathers) was published in 2008.
In 2015, she published her tenth novel, Y Bwthyn (Y Lolfa, 2015), a novel that revolves around three characters - Enoch, Isaac and Owen.