She was the second of the four children (Gwen, Thornton, Augustus and Winifred) of a solicitor, Edwin William John, and his wife Augusta (née Smith).
She studied at the Slade, following her younger brother Augustus, and in 1898-1899, on a visit to Paris, studied under Whistler at the Académie Carmen. In 1904 she was again in Paris, and modelled for Auguste Rodin, forming a passionate relationship with him. She modelled for the Memorial to Whistler projected but never completed by Rodin.
Although she exhibited her work in the early years of the 20th century she became increasingly reclusive, and from 1926 lived in Meudon.
Her distinctive colour and technique, and the restrained apparent simplicity of her figure compositions (which sometimes show a Whistlerian influence), are now much admired, eclipsing the fame of her younger brother Augustus.
Newton, J., and M. MacDonald, 'Rodin: The Whistler Monument', Gazette des Beaux-Arts, vol. 92, 6th series, 1978, pp. 221-31; Langdale, Cecily, Jenkins, David F., & John, Gwen, Gwen John (1876–1939): An Interior Life, New York, 1986. Langdale, Cecily, Gwen John, New Haven and London, 1987.
'Gwen John 1876–1939', Tate website; 'Gwen John 1876–1939', ArtUK; 'Gwen John', Wikipedia.