The surname Olgiati is of toponymic origin and derives from various places of northern Italy such as Olgiate Comasco, Olgiate Molgora and Olgiate Olona. On this point E. De Felice and E. Rossoni agree, noting that the surname was formed to indicate provenance from these centres, situated mainly in the Como, Lecco and Varese areas.

E. Rossoni adds that the place name Olgiate could derive from the Latin name Ulvius or Ulbius with the suffix -ate, which indicates belonging or territorial relation. He also documents the historical presence of the surname in different periods, which confirms its consolidation as a hereditary surname in the Lombard sphere and nearby areas such as the canton of Ticino.