The surname Marchetto is a derivative of the personal name Marco (an anthroponymic surname), which continues the ancient Latin name Marcus, whose meaning is associated with "consecrated to the god Mars", the Roman divinity of war. This name spread widely in Italy from antiquity and was consolidated in the Middle Ages thanks to the religious prestige of Saint Mark the Evangelist, particularly in the regions of north-eastern Italy, where his cult had a strong presence.

According to F. De Laurentiis, the surname is linked directly with this tradition, while E. Costantini reads it as an affectionate diminutive of the name Marco. In this sense, forms such as Marchetto or Marchèt reflect processes typical of Italian and of the dialects of the north, where diminutive suffixes express closeness or family belonging.

As for its diffusion, variants such as Marchèt appear with the greatest frequency in the Feltre area, while Marchetto is fairly widespread in Veneto, with a documented presence also in areas such as Lignano, in Friuli. These differences reflect dialect adaptations proper to each region.

In sum, Marchetto is a surname of anthroponymic origin derived from Marco, with a meaning linked to the Roman and Christian tradition, which spread especially in north-eastern Italy and shows regional variants associated with local dialect usage.