As a young man, Santiago Alvarez studied in the USA and worked there at menial jobs. After his return to Cuba in the mid-1940s, he worked as a music archivist in a TV station and participated in the activities of the Cuban communist party and "Nuestro Tiempo," a political-cultural society.

With no formal training as a filmmaker, Alvarez made his first documentaries at the age of 40, in the wake of the Revolution. He was a founding member of ICAIC, the Cuban film institute established in 1959.

Though he has directed one fiction feature and headed ICAIC's Latin American Newsreel division, Alvarez's reputation is as a brilliant and innovative documentary filmmaker. His highly partisan political themes, such as anti-imperialism and support for Fidel Castro and the Revolution, are expressed in an eclectic style that draws on creative improvisation. In his famous anti-imperialist satire, "LBJ" (1968), and other documentary shorts produced in the 1960s, the filmmaker employed a "nervous montage" approach that stressed a skillful use of sound and creative editing techniques to tie together a fast-paced collage of disparate "found" materials such as cartoons, still photos, and clips from Hollywood movies.

Among the best known of Alvarez's documentary features are "79 primaveras" (1969), a poetic tribute to Ho Chi Minh; and "De America soy hijo...y a ella me debo" (1972) and "Y el cielo fue tomado por asalto" (1973), which both chronicle Castro's international tours.