She was twice nominated for the Academy Award for Best Supporting Actress for her performances in Midnight Cowboy (1969) and Farewell, My Lovely (1975).
Miles was a fixture in New York City society, having lived there her entire life.
She performed in many Off-broadway shows, including starring in a one-woman musical based on her life, titled It's Me, Sylvia! in 1981.
A documentary about her life titled I Was Always Sylvia aired on New York City public television channel WNET as part of The 51st State series.