The authors agree that the surname derives from the Germanic personal name compounded from *waldaz ("mighty, chief, commander") and *harja ("army, people in arms"), with the meaning "mighty in the army" or "chief of the army". This base gave rise to the name Gualtiero —the equivalent of the German and English Walter— and spread widely across medieval Europe.

E. De Felice notes that in Italy the surname reflects a Frankish tradition, documented between the 9th and 11th centuries in forms such as Vualterius, Walterius and Gualterius, with the shift from d to t before h and the palatal metaphony of -ari into -(i)eri. Its spread was also influenced by medieval epic through the Old French Galtier and Gautier.

F. Miranda adds that the surname may likewise derive from the Norman name Gualtier or from the Latin cognomen Gualterus, and notes the existence of related place names: the comune of Gualtieri, in the Reggio Emilia area, and that of Gualtieri Sicaminò, in the Messina area. The surname is distributed throughout the Italian peninsula, with a particularly notable presence in Emilia-Romagna, Calabria, Lombardy, Tuscany, Lazio and Abruzzo.

V. Blunda, from a Sicilian perspective, characterizes the surname as a northern variant of Galtieri with initial palatalization, and agrees with the other authors on the Germanic base wald + harja.