The surname Bixio is characteristic of Liguria, especially of the Genoa area, and has a clearly nickname-based origin. According to E. De Felice, it derives from the medieval nickname Bìxio, documented as early as 1162 in Genoa in the Latinised form Bixius, formed from the Ligurian adjective bìx(i)u ("bigio", that is, grey). This type of nickname was habitually used to describe physical traits, in this case probably the colour of the hair or beard.

Along the same lines, E. Rossoni confirms that it is a typically Ligurian surname, with a strong presence in the Genoa area and nearby localities such as Sestri Levante. He also interprets its origin as a dialectal nickname related to the grey colour (bigi), reinforcing the idea of a denomination based on visible characteristics of the ancestor.

Taken together, both interpretations agree in pointing to a nickname-based origin linked to physical appearance, with a clear regional implantation in Liguria and a continuity documented since the Middle Ages.