Hubert Harrison was born in St. Croix of the Virgin Islands in 1883. At the age of seventeen he travelled to New York City where he worked as a bellhop and an elevator operator. He also attended night school and studied sociology, science, psychology, literature, and drama.
Harrison's studies radicalized him and he became a member of the Industrial Workers of the World. He later joined the Socialist Party where he met other African American radicals such as Philip Randolph, Chandler Owen, and Claude McKay. He impressed them with his intellect and was given the nickname, the "Black Socrates". According to Barbara Bair, Harrison "protested the quick abandonment of the recruitment campaign among blacks in 1912... while openly criticizing the racial prejudice manifested by some party leaders."
Harrison joined Bill Haywood, Carlo Tresca, and Elizabeth Gurley Flynn in the Industrial Workers of the World campaign during the Paterson Silk Industry Strike in 1913. This alienated him from the executive committee of the Socialist Party. In 1914 he was suspended from the party.
Max Eastman, editor of the The Masses, employed him on his journal. Harrison also edited The Voice and contributed to the The Messenger, The Call, The New Republic, the New York Times and the New York World. He also published two important books, The Negro and the Nation (1917) and When Africa Awakes (1920).
Harrison was a strong opponent of United States involvement in the First World War. This caused him to break with William Du Bois who had argued in The Crisis that: "Let, us, while this war lasts, forget our special grievances and close our ranks."
Harrison also lectured on socialism and African American civil rights from street corners and in September, 1922, the New York Times reported that he was drawing crowds of over 10,000 people and the New York City police had to stop the traffic. His friend, Joel Rogers, recalled that "he spoke wherever an audience could be had on subjects embracing general literature, sociology, Negro history, and the leading events of the day."
It is claimed that Harrison had a great influence on Marcus Garvey. Harrison, who was now claiming that race was more important than class and after leaving the Socialist Party he joined Universal Negro Improvement Association (UNIA). Harrison also edited the organizations journal, The Negro World, for four years. He also worked as a staff lecturer for the New York City Board of Education.
Harrison advocated the creation of a separate black state within the territory of the United States, and in 1925 he founded the International Colored Unity League and a new periodical, the Voice of the Negro.
Hubert Harrison died of an appendicitis-related illness on 17th December 1927.