Capers was born in Sumpter, South Carolina, and attended Howard University in Washington, D.C. and the Juilliard School in New York. She performed in Yiddish theater, understudied Adelaide Hall in Jamaica, and performed in the 1959 Harold Arlen-Johnny Mercer musical Saratoga. She also appeared in a number of television shows, including Have Gun, Will Travel and Mannix (for which she was nominated for an Emmy Award), and films, including the 1972 Lady Sings the Blues, which starred Diana Ross, The Toy, and What's Love Got to Do With It. Capers also founded the Lafayette Players, a Los Angeles repertory theater company comprised of black actors.
She was the recipient of the National Black Theatre Festival Living Legend Award, the Paul Robeson Pioneer Award, and the NAACP's Image Award for theater excellence.
Capers is survived by a son and a brother.