Moon was born in Cleveland, Ohio in 1901. His father Roddy K. Moon established the Cleveland branch of the NAACP in 1912. Moon attended Howard University where he served as the editor of the school's University Journal. He then received a master's degree in journalism from Ohio State University. Moon's goal at the time was to become the first black journalist to work for a white-owned newspaper. However, in 1925 he went to work in public relations at the Tuskegee Institute instead. In 1931, he achieved his dream of becoming a newspaperman when he was offered a job at the African-American weekly The Amsterdam News. He moved to New York City and began writing book reviews and essays for the publication. The same year, he collaborated with fellow News journalist Ted Poston on a series of articles focusing on capital crimes. The two men became roommates and remained best friends for the rest of their lives. In 1932, they traveled to the Soviet Union with Langston Hughes and Moon's future wife Mollie Lewis to make an anti-segregation film called Black and White. The film was cancelled at the last minute by the Mezhrabpomfilm studio, causing Moon to have a lifelong disillusionment with the Communists. Unbeknownst to Moon, engineer Hugh Lincoln Cooper had threatened to stop work on the high-profile Dnieper Dam if the Soviet government did not halt the production of the film, which he viewed as un-American. After he returned to the US, Moon got a job with the Public Works Administration under Harold L. Ickes and continued to write for The Amsterdam News. Moon was fired from the paper after he encouraged the staff to join The Newspaper Guild union. He then went to work for the Federal Writers' Project until federal funding for it was ended in 1939. Moon applied to the New York Times, but was rejected. He found work in Washington, D.C. working for Robert C. Weaver on Franklin D. Roosevelt's Black Cabinet as a race relations advisor. After the war, he worked as an organizer for the PAC of the CIOtrade union. In 1948, Moon began working for the NAACP as their public relations director. Moon held the position until 1974. During his tenure at the NAACP, he promoted voting rights and encouraged the organization to work harder to elect politicians friendly to their cause. While at the NAACP, he also wrote the book Balance of Power and edited a collection of W. E. B. Du Bois' writings.
Moon married Mollie Lewis on August 13, 1938. The couple became well-known for throwing integrated society parties that allowed black and whiteNew Yorkers to meet and connect with each other. Their reputation was satirized in Chester Himes' 1961 novel Pinktoes.
