A statement posted to her Instagram account read: "We are heartbroken to announce the passing this morning of our beloved Sophie (aka Maddy, aka Mummy). She died peacefully, with her final days filled with her true loves: family and music and warmth and Christmas and joy.
"We can't imagine what life will be like without her radiance and love of life.
"Despite her illness, which she bore with unimaginable courage, Sophie counted herself truly blessed - to have such wonderful family and friends, and to have had the extraordinary success of her writing career. She took nothing for granted and was forever grateful for the love she received.
"She will be missed so much our hearts are breaking."
Madeleine Sophie Wickham, who wrote under the pen name Sophie Kinsella, announced in April 2024 she had been diagnosed with an aggressive form of brain cancer.
She wrote on Instagram at the time: "At the end of 2022 I was diagnosed with glioblastoma, a form of aggressive brain cancer.
"I did not share this before because I wanted to make sure that my children were able to hear and process the news in privacy and adapt to our 'new normal."
She said in the post that she has been receiving chemotherapy and radiotherapy.
She released The Burnout in October 2023 and her other best-selling books include Can You Keep A Secret? and The Undomestic Goddess.
Her novels have sold more than 45 million copies in more than 60 countries, and have been translated into more than 40 languages.
The first two works in her hit eight-book Shopaholic series, The Secret Dreamworld Of A Shopaholic and Shopaholic Abroad, were adapted into the 2009 film Confessions Of A Shopaholic, starring Isla Fisher.
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