During this same time Sleet served in an all-African American unit in World War II and was an assistant at a commercial operated studio.

After his education at NYU he was a sports journalist for the Amsterdam News in New York and then John P. Davis' magazine Our World.

[3] Over the next 41 years, he captured photos of young Muhammad Ali, Dizzy Gillespie, Stevie Wonder, Emperor Haile Selassie I, Jomo Kenyatta, former ambassador Andrew Young in a blue leather jacket and jeans in his office at the United Nations, Ghana's Kwame Nkrumah, Liberia's William Tubman and Billie Holiday.

When Coretta Scott King found out that no African American photographers had been assigned to cover her husband's funeral service, she demanded that Sleet be a part of the press pool.

[9] Besides his photo of Coretta Scott King, he also captured grieving widow Betty Shabazz at the funeral of her husband Malcolm X.