He became a leader in activism against colonial rule. He gained recognition by writing frequent letters on the issues to the "Daily Gleaner" newspaper. In 1937 he was elected as treasurer of the Jamaica Workers' Union (JWU), which had been founded by labour activist Allan G.S. Coombs. During the 1938 labour rebellion, he quickly became identified as the spokesman for striking workers, who were mostly of African and mixed-race descent. Coombs' JWU became the Bustamante Industrial Trade Union (BITU) after the revolt, and Bustamante became known as "The Chief".