Coltrane, 69, died of respiratory failure, The New York Times said. She lived near the Sai Anantam ashram in Agoura Hills, Calif., which she founded in 1983, where 25 to 30 full-time residents study scriptures of ancient India, as well as Buddhist and Islamic texts.
Coltrane -- who played piano in her husband's band -- managed Coltrane's estate, his publishing company, Jowcol Music and the John Coltrane Foundation, which awards scholarships to music students.
As a pianist, her style was marked by arpeggios that suggested the harp, which she also played. After her husband's death, Coltrane embarked on a solo recording career.
She once said Coltrane helped her to play "thoroughly and completely," the Times said. Not only did he help her stretch her musically, she said, but also philosophically by introducing her to Eastern religion and philosophy, which became the focus of her life.
Alice Coltrane, who died Friday, is survived by two sisters, a daughter, two sons and five grandchildren.