Chesacco is a very rare Italian surname, not documented as an autonomous entry in the main dictionaries of Italian surnames consulted. Its distribution seems to be concentrated in the northeast of Italy, probably in the area of Friuli-Venezia Giulia or in the bordering zones of eastern Veneto.

The ending -acco is characteristic of Friulian onomastics and appears in numerous surnames and place names of the region. On this basis, the most probable etymology places the origin of the surname in the Friulian linguistic sphere.

Various hypotheses have been proposed to explain its formation. One of them relates it to a derivative of chiesa ("church", from the Latin ecclesia), used as a surname of provenance to identify a person who resided near a church or who came from a locality characterised by the presence of a parish. Another possibility is that it derives from an old Friulian microtoponym today disappeared or scarcely documented, formed with the suffix -acco, frequent in the regional toponymy. A link with a medieval anthroponym related to Cesare has also been suggested, although this interpretation has less documentary support.

Given that the surname does not figure as an autonomous entry in the main Italian onomastic repertoires consulted and that its diffusion is very limited, the proposed etymologies must be considered indicative.