Maynor was born September 3, 1910 in Norfolk, Virginia. She earned her Bachelor of Arts degree from Hampton Institute in 1933 and another Bachelor of Arts degree from the Westminster Choir School in 1935. Maynor made her debut at The Town Hall in New York in December, 1939 and as a result of that performance received the Town Hall Endowment Series Award for 1940.
Despite the racism that precluded her from performing at many opera houses, Maynor toured extensively throughout the U. S., Europe and Latin America. In 1964, she founded the Harlem School of Arts to provide music education to the children of Harlem. Under her leadership the school grew from 20 students to 1,000 at the time of her retirement in 1979.
In 1979, Maynor became the first African American to serve on the Board of Directors of the Metropolitan Opera. Her biography, “Dorothy Maynor and the Harlem School of the Arts: The Diva and the Dream,” was published in 1993.