Born April 25, 1911, to William and Emma Spencer, Kenneth Spencer grew up in the Boyle Heights suburb of Los Angeles (now known as Hollenback Heights), and graduated from Roosevelt High School in 1930.

Spencer's voice hinted at greatness as early as six years, when it was described as "too rumbly or deep" for his age. While attending Roosevelt High School, Spencer was determined to capitalize on the peculiar nature of his voice and cultivate it.  He was able to secure voice lessons from qualified teachers in Los Angeles through the 28th Street YMCA, the Los Angeles Music School Settlement and other public institutions. Spencer became an outstanding soloist and participated in dramas and operas, and with other vocalists, created the "Two-Eight" YMCA Quartet.

After graduating from Roosevelt in 1930, Kenneth Spencer appeared as a special soloist at the Hollywood Bowl, singing "The Horn" a hunting song in which he used a 2-octave range, "ending on his famous low C". During that time, Spencer worked as a road builder and gardener, and along with the help from some donors, moved to San Francisco in 1931.

Spencer performed with the Two-Eight at various nightclubs, living mostly on milk and the meal provided as partial pay for singing.  In San Francisco, Spencer met people who were involved in protecting the rights of minorities, and those involved in the development of organizing workers unions. At the same time, the artistic atmosphere blossomed under the protection of the W.P.A. projects designed to help development and production in the arts.

When the "Two Eight"t dissolved, Spencer set out on his own and secured a contract with the San Francisco radio station KPO, to do a weekly series of singing and readings called "Truthful Deacon Brown." During this time, Spencer was fortunate to receive financial assistance from wealthy music lover Noel Sullivan for voice lessons for two years. 

Spencer married his first wife, Dorothy Fisher in San Francisco in 1932, at age nineteen (they divorced in 1948). While in San Francisco, Kenneth gave his first concerts in Canada and throughout the west coast. He caught the attention of tenor Roland Hayes who assisted him in getting a scholarship to the Eastman School of Music at the University of Rochester in 1934.

In 1938, after graduation from the Eastman School, Spencer traveled and performed as Joe in "Showboat" with the St. Louis Opera Company. On July 4th that same year, he performed in the new opera "Gettysburg" at the El Capitan Theatre in Los Angeles. Commissioned by the Federal Music Project, the performance was broadcast nationally over NBC’s Blue Radio Network. Spencer also sang when the opera had its premier at the Hollywood Bowl on September 23rd, 1938. He then moved to New York and secured a standing engagement singing at the storied New York City nightclub, Cafe Society, where he befriended many notable African Americans.

In 1940, Spencer was the understudy for Paul Robeson in the short-lived Broadway musical "John Henry." He made his professional recital debut in 1941, at New York City's Town Hall, and six years later, he performed at Carnegie Hall. In 1943, Spencer starred in the Metro-Goldwyn-Meyer films, "Cabin in the Sky" and "Bataan." That same year, he organized a U.S.O. tour to entertain African American troops. In 1946, Spencer performed in the hit Broadway musical "Show Boat," where he sang what would become his signature song, 'Ol’ Man River.'

In 1949, Spencer was invited to France to perform at the International Music Festivals in Nice and Paris and received an enthusiastic response to his talents. Receiving numerous offers to perform in Europe, and frustrated with the pervasive racial prejudice in the United States, he moved to Paris. He married his second wife, New York journalist Josephine Levin, that same year and eventually settled in Wuppertal, Germany in 1953. They had a son William, who was born in 1951.

Kenneth Spencer spent the next fourteen years performing in concerts, operas, and plays throughout Europe, with tours in the United States during the winter months. Spencer also appeared in the French film "Les Joyeaux Pellerins," (1951), and starred in a few German films; "Mein Bruder Joshua" (1956), "Gruß und Kuß vom Tegernsee" (1957), "An Jedem Finger Zehn" (1959), and "Unser Haus in Camerun" (1961). Spencer also made a number of recordings with Columbia Masterworks Records during the fifties and sixties which consisted of classical music, spirituals, and folk songs.

Kenneth Spencer's life was tragically cut short when he died in the crash of Eastern Air Lines Flight 304, at Lake Pontchartrain after leaving the New Orleans International Airport, on February 25, 1964. Spencer was on his way to New York to perform at a civil rights event. He is buried at Evergreen cemetery in Los Angeles.