Hughes, like many black writers and artists of his time, was drawn to the promise of Communism as an alternative to a segregated America. Many of his lesser-known political writings have been collected in two volumes published by the University of Missouri Press and reflect his attraction to Communism. An example is the poem "A New Song".
In 1932, Hughes became part of a group of black people who went to the Soviet Union to make a film depicting the plight of African Americans in the United States. The film was never made, but Hughes was given the opportunity to travel extensively through the Soviet Union and to the Soviet-controlled regions in Central Asia, the latter parts usually closed to Westerners. While there, he met Robert Robinson, an African American living in Moscow and unable to leave. In Turkmenistan, Hughes met and befriended the Hungarian author Arthur Koestler, then a Communist who was given permission to travel there.
As later noted in Koestler's autobiography, Hughes, together with some forty other Black Americans, had originally been invited to the Soviet Union to produce a Soviet film on "Negro Life", but the Soviets dropped the film idea because of their 1933 success in getting the US to recognize the Soviet Union and establish an embassy in Moscow. This entailed a toning down of Soviet propaganda on racial segregation in America. Hughes and his fellow Blacks were not informed of the reasons for the cancelling, but he and Koestler worked it out for themselves.
Hughes also managed to travel to China and Japan before returning to the States.
Hughes's poetry was frequently published in the CPUSA newspaper and he was involved in initiatives supported by Communist organizations, such as the drive to free the Scottsboro Boys. Partly as a show of support for the Republican faction during the Spanish Civil War, in 1937 Hughes traveled to Spain as a correspondent for the Baltimore Afro-American and other various African-American newspapers. In August 1937, he broadcast live from Madrid alongside Harry Haywood and Walter Benjamin Garland. Hughes was also involved in other Communist-led organizations such as the John Reed Clubs and the League of Struggle for Negro Rights. He was more of a sympathizer than an active participant. He signed a 1938 statement supporting Joseph Stalin's purges and joined the American Peace Mobilization in 1940 working to keep the U.S. from participating in World War II.
Hughes initially did not favor black American involvement in the war because of the persistence of discriminatory U.S. Jim Crow laws and racial segregation and disfranchisement throughout the South. He came to support the war effort and black American participation after deciding that war service would aid their struggle for civil rights at home. The scholar Anthony Pinn has noted that Hughes, together with Lorraine Hansberry and Richard Wright, was a humanist "critical of belief in God. They provided a foundation for nontheistic participation in social struggle." Pinn has found that such writers are sometimes ignored in the narrative of American history that chiefly credits the civil rights movement to the work of affiliated Christian people.
Hughes was accused of being a Communist by many on the political right, but he always denied it. When asked why he never joined the Communist Party, he wrote, "it was based on strict discipline and the acceptance of directives that I, as a writer, did not wish to accept." In 1953, he was called before the Senate Permanent Subcommittee on Investigations led by Senator Joseph McCarthy. He stated, "I never read the theoretical books of socialism or communism or the Democratic or Republican parties for that matter, and so my interest in whatever may be considered political has been non-theoretical, non-sectarian, and largely emotional and born out of my own need to find some way of thinking about this whole problem of myself." Following his testimony, Hughes distanced himself from Communism. He was rebuked by some on the Radical Left who had previously supported him. He moved away from overtly political poems and towards more lyric subjects. When selecting his poetry for his Selected Poems (1959) he excluded all his radical socialist verse from the 1930s.