Fuller enlisted in the U.S. Navy during World War I. He served as a radio operator and later as a crash boat commander, gaining experience in navigation, communication, and leadership.

Fuller's naval experience included serving on a crash boat designed to rescue downed aviators. This role exposed him to the fragility of human life and the importance of innovative solutions to practical problems.

After the war, Fuller married Anne Hewlett. He became involved in various business ventures, including the Stockade Building System company, focusing on lightweight, modular housing. These ventures ultimately faced financial difficulties, contributing to a period of personal and professional crisis.