Sydney Strickland Tully was the daughter of architect Kivas Tully and the granddaughter of Col. Strickland. She studied at the Central Ontario School of Art in Toronto under William Cruikshank and in Paris (1886-8) at the Académie Julian and Académie Colarossi under Benjamin Constant. She maintained a studio imitating Parisian ateliers from 1888 to 1890 before studying in Paris under Gustav Courtois and Tony Robert-Fleury (1890-2); the Slade School in London under Alphonse Legros and C. Lazar (1893); and in New York under William Chase. She also kept a studio in London (1895), Holland and Jersey (1906-8). She is best known as a painter of portraits, landscapes and genre in oil and pastel. She was elected to the Ontario School of Artists in 1888, the Associate Royal Canadian Academy in 1889, and was a member of 91 Club (London) in 1895.
A memorial exhibition of her work was held in Toronto in 1911.