The origins of Fonzaso should be placed in Roman times. The locality benefited from the proximity to Feltria, at that time the town hall, and to the transit of the Via Paolina, a branch of the more famous Via Claudia Augusta Altinate.
The erection of two castles dates back to the period of the barbarian invasions, one located near the saddle of Arten, the other near the còvolo di San Michele and owned by the Ghibelline family of Fonzasia.
For the rest, the town has followed the fate of nearby Feltre, seat of a bishop's county and throughout the Middle Ages involved in the struggles between the Empire, the Republic of Venice and the local lords. The territory became definitively Venetian in 1404. Originally from Fonzaso were the great sixteenth-century master swordsmen Zandonà and Andrea Ferara and Giacomo da Fonzaso, whose high quality products were renowned in almost the entire Western world of the time. Some of their swords have even been purchased by some rulers. Located in a strategic position towards Trentino, Fonzaso enjoyed the fertility of its countryside and the presence of the Cismon stream, used for the floating of timber, even if there were moments of difficulty caused by fires and floods. The eighteenth century was perhaps the period of maximum splendor, as evidenced by the construction of some Venetian villas.