She was born in Fullerton, Orange County, California, the daughter of an English father and a mother from New Zealand. She attended Eagle Rock High School in northeast Los Angeles, California, graduating in 1941. She then attended Occidental College in Los Angeles from 1941 to 1944. She moved to New York in 1946, working as a composer, conductor, and recorder player, and spending most of her professional life in New York City. Her compositions often feature microtonality and are strongly influenced by early music. She developed special recorders with extra holes, as well as special fingerings for the recorder to allow for the playing of quarter tones. Her Indian Summer: Three Microtonal Antiphons on Psalm Texts for two baritones and chamber ensemble combines the use of quarter tones with a Latin text.
From 1947 to 1970 she spent her summers as the music director of Camp Catawba for Boys, located near the Blue Ridge Parkway on the Boone side of Blowing Rock, North Carolina. Pianist Grete Sultan also worked here every summer. In 1985, Tui inherited the camp grounds from her life long partner, poet and scholar Vera Lachmann (1904–1985), who had founded the camp in 1944, and lived there year round from then until her death.
Her works have been performed by such performers as the Kohon Quartet, pianists Grete Sultan and Loretta Goldberg, and recorder player Pete Rose.
She is named for the tui, a bird native to New Zealand, where her mother was born.
Bredow, Moritz von. 2012. Rebellische Pianistin. Das Leben der Grete Sultan zwischen Berlin und New York. Mainz: Schott Music. ISBN 978-3-7957-0800-9 (This book contains many aspects of the lives and the art of Tui St George Tucker, Vera Lachmann and Grete Sultan).