E. De Felice documents the surname from 1266–70 in Naples, where it is recorded as Rogerius Malerba. According to this author, the surname derives from a nickname formed from malerba —a word compounded from mala, "bad", and erba, "grass"—, with the sense of "plant that infests and damages crops" and, figuratively, "a bad or dangerous person". F. De Laurentiis agrees with this etymology and adds that the surname appears sporadically throughout Italy, although it is frequent only in Liguria and in Lombardy.

E. Rossoni shares the etymological base —the nickname malerba applied to someone of bad character— but notes a somewhat different geographical distribution: he identifies an established area of the surname in Puglia and points to the probable existence of other cores, that is, other specific and scattered areas of Italy where the surname is present independently.