Horace Bristol studied architecture in the 1920s at the University of Southern California, and then in Germany and France. While in Munich he bought a 35mm camera to record European architectural monuments. On returning to the United States, Bristol turned to journalism, and edited a small weekly newspaper in California. In the 1930s he sold the newspaper and enrolled in photography classes. In 1933 he opened his own studio, and supported himself by making portraits, mostly of children. He later moved with his family to San Francisco, where he was a neighbor of Ansel Adams. Through Adams, Bristol met many important photographers, including Edward Weston and Imogen Cunningham.
Bristol welcomed commercial assignments and his work appeared in such magazines such as Fortune, Time, and Life. He often developed his own projects, including a collaborative photo-essay of Southern sharecroppers with John Steinbeck. During World War II Bristol was chosen by Edward Steichen to document the Navy's war effort. Bristol covered the invasion of Africa, the War in the Aleutians, and combat life on carriers in the Pacific.
After the war, Bristol was sent by Fortune to Asia, where he eventually opened his own photo agency, and until 1956 he traveled and photographed exotic locations and important figures. After the death of his first wife, he gave up photography. He later remarried and moved first to Mexico and then to California, where, after many years, he began to photograph again.