Mabel Lucie Atwell was born in Mile End London, on the 4th June 1879. She went to a private school, and went to Coopers Company School and to the Regent Street School. She studied art at Heatherley's and St Martin's school of Art, but left as she preferred working from her imagination instead of still-life and classical subjects. After she sold work to the Tatler and Bystander, she was taken on by the agents Francis and Mills, and did magazine illustrations. Around 1900 she began receiving commissions for book illustrations.
In 1908, she married painter and illustrator Harold Cecil Earnshaw, with whom she had a daughter Marjorie and two sons. She illustrated children's classic such as Mother Goose (1919), Alice in Wonderland (1911), Hans Anderson Fairy Tales (1914), The Water Babies (1915) and Peter Pan and Wendy. She continued to illustrate magazines, she did advertising, and greeting cards.
In the early days her work was along the same style as other artists ant the time, her friend Hilda Cowham and Jessie Wilcox Smith and others. From 1914 onwards, however, she developed her trademark style of rotund cuddly infants, which became ubiquitous across a wide rang of markets: cards, calenders, nursery equipment and pictures, crockery and dolls.
In 1921 J.M.Barrie personally requested her to illustrate the gift-book edition of Peter Pan. The Lucie Atwell Annual was published from 1922 to 1974, its continuance ten years after her death being possible by extensive re-use of images, a practice established in the 190's picture books of her work.
In 1926 Shelley Potteries commissioned Mabel Lucie Attwell to produce designs for children’s china ware, following the successful sales of china decorated with designs by Hilda Cowham. Atwell’s first six designs portrayed scenes involving children, animals and small green elves in green suits - these were called ‘Boo Boos’ and used on cups, mugs, bowls etc.
She died at her home in Fowey, Cornwall, in 1964, and her business was taken over by Marjorie.