Born in Wood Lane, Falmouth (24 February 1861), Maria was the sister of the artist Henry Scott TUKE. As a child she was educated privately with the Fox children (Caroline FOX and Anna Maria FOX), and then further at Weston-super-Mare. While her brother studied at the Slade her family moved to London, but she was not allowed the same privileges as he, despite an innate talent for art. She befriended a number of her brother's friends, including Thomas Cooper GOTCH, and despite no formal training painted landscape and portrait subjects, mainly in watercolour.

She married Dr Harrington Sainsbury in 1899, with whom she had four children.  She continued to paint after her marriage, signing her work MTS.  Her shipping watercolours are similar to those of her brother, and she was with him at his cottage overlooking Swanpool in Falmouth when he died. As Maria Tuke Sainsbury, she wrote a book about her brother Henry Scott TUKE, RA, RWS: A Memoir (1933).

A Quaker by birth and up-bringing as were the Fox family, Maria converted to Catholicism after the death of her husband, and spent her last years in a Catholic Convent on the Bayswater Road, London. She died on 15 August 1947 in Richmond-upon-Thames, aged 86.  Five of her works, all watercolours and all from Private collections, were exhibited at the Falmouth Group Show of Women Artists in 1996.