The British woman, whose real name is Madeleine Sophie Wickham, turned 55 years old.
"She died peacefully after her last days were filled with what she loved: family and music and warmth and Christmas and joy," reads a post on the author's Instagram account, published on Wednesday afternoon.
Wickham is known for her feel-good books that have sold tens of millions of copies worldwide, including "Confessions of a Shopaholic," which was made into a film in 2009 starring Isla Fisher.
Wickham was diagnosed with an aggressive form of brain cancer in 2022. Last year, the semi-biographical book “What Does It Feel Like” was released, which reflects her own struggle with cancer.
