He had five brothers and lost his father (1905), forcing him to emigrate to Germany and metalworks employment in Köln (1905). He returned to serve in the military (1909) and joined car coachbuilder Carrozzeria Varesina in Varese, while studying at the Santa Maria design school.
During World War I he moved to Torino and joined the Pomilio aircraft manufacturer, learning lightweight bodycrafting (1915-1919). He established Carrozzeria Ugo Zagato & Co., a workshop in Milano (1919), where he built close ties with Alfa Romeo.
His workshop was destroyed and rebuilt as La Zagato outside Milano after World war II, joined by his sons Elio Zagato (born 1921) in 1946, and Gianni Zagato (born 1929). His sons continued operations on Ugo Zagatos passing (1968).