Reeves was born in Detroit, Michigan, to a very musical family. Her father, who died when she was two years old, was also a singer. Her mother, Vada Swanson, played trumpet. A cousin, George Duke, is a well-known piano and keyboard player and producer. Dianne and her sister Sharon were raised by their mother in Denver, Colorado. As a child, Dianne took piano lessons and sang at every opportunity. When she was 11 years old, her interest in music was enhanced by an inspiring teacher who thought that music was the best way to bring students together. Dianne discovered a love of music and that she wanted to be a singer.
Her uncle, Charles Burrell, a bass player with the Denver Symphony Orchestra, introduced her to the music of jazz singers, from Ella Fitzgerald to Billie Holiday. She was especially impressed by Sarah Vaughan.