The authors agree that this is a surname of toponymic origin, derived from the place called Perego, in the Lecco area (Lombardy). E. De Felice places it in general terms in upper Lombardy, linking it with the province of Como. E. Rossoni specifies that its presence is concentrated in the provinces of Milan, Varese, Como, Lecco and Bergamo, and documents its transformation into a surname from the 13th century, when Leone da Perego served as archbishop of Milan between 1241 and 1257. Rossoni also records the notary Erasmo Perego of Barzanò in 1524, and mentions that in 1754 the sculptor Giuseppe Perego was commissioned by the Fabric of the Duomo of Milan to create the Madonnina that crowns the highest spire of the cathedral.

R. Brondolo proposes a different etymology: the surname would come, by rhotacism —that is, the change of a consonant into r—, from the term pelago, with the sense of "arm of a lake." Brondolo further adds a presence of the surname in the Tortona area, in Piedmont.