Hart was born in Baltimore, Maryland, in 1910. He started his career as a professional jazz pianist in 1929 when he joined Gene Coy‘s ensemble. He was also part of Jap Allen‘s band from 1929 to 1931.Hart played piano in Blanche Calloway‘s big band from 1931 to 1935 and was based in New York City from 1936.
In the late 1930s he played with Lionel Hampton and Chu Berry. In the first half of the 1940s he played with John Kirby, Roy Eldridge and Hot Lips Page, among others. In the last few months before his death Hart collaborated with some of the most important figures of the bebop era, such as Charlie Parker, Dizzy Gillespie and Don Byas, and led recording three sessions. He died of tuberculosis in March 1945, at the age of 35