Kuusio is rare as a paikannimi (place name) and it is known as a tilannimi (farm name) in Eurajoki, Hauho, Iisalmi and Isojoki.
In particular it has been shown that from the western dialect regions, there are names in which the ~io ending reverts back to the word joki (river). For example, the name Vuolio, becomes Vuolijoki. The name Kuusio has developed from the name Kuusijoki.
As a surname, Kuusio does not have any particular name-bearing region or area, but it does appear in several different localities including the country sides of Seinäjoki, Rauma, Lahti, Jyväskylä, Kouvola and Lappeenranta and Helsinki.