The authors agree that this surname derives from medieval hypocoristic forms —that is, shortened versions— of names of Germanic origin related to Guglielmo. E. De Felice notes that the medieval forms Ghìglia, Guìglia, Vìglia and Bìglia, documented from the 9th century, represent variants arisen through apocope of names formed with the Germanic element *wiljan- ("will"), with different adaptations of the phoneme w- to Italian phonetics (g, gu, v, b). He associates Ghiglia and Guiglia with Liguria; Viglia with Piedmont, Emilia-Romagna and Campania; and Biglia with Lombardy, Emilia-Romagna and Campania.

E. Rossoni adds that it could also derive from the Roman gens Aquilia or from the medieval name Guilia, documented in Modena in 1182. He further notes that its fixing as a surname is documented in the second half of the 17th century north of Milan. Geographically, he places Ghiglia between the Cuneo area and Liguria; Ghigliano in the Cuneo area; Ghigliazza in the Ligurian Riviera di Ponente, especially in the Savona area, the Genoa area and Imperia; Ghiglietti between the Milan, Lodi and Pavia areas, with another isolated pocket in that of Turin; and Ghigliotti and Ghigliotto in Liguria.