The two main sources consulted agree that Montalti is a variant of the surname Montalto, with a characteristic presence in the area of Forlì, in Emilia-Romagna. Its origin is toponymic, linked to one of the many place names Montalto distributed across Italy.

E. Rossoni suggests that the surname may derive specifically from Montalto di Sarsina, a locality situated in the same area of Forlì. F. Miranda broadens the range of possible origins, adding Montalto Uffugo, in the province of Cosenza, and Montalto di Castro, in the province of Viterbo, without ruling out other place names of the same form scattered across the Italian peninsula.

Miranda further details the geographical distribution of the surname: although it is concentrated mainly in Romagna, it also appears in specific, localized areas of Tuscany, Lombardy, Lazio, Umbria, Piedmont, Calabria, Sicily, and Trentino-Alto Adige. In Sicily it is recorded in the areas of Catania, Ragusa, and Enna.

Rossoni adds that in Sicily the base form Montalto carries ancient noble roots associated with the title of Baron, suggesting a family tradition of long standing on the island. It is also noted, in a separate source, that the surname may likewise connect to the place name Montaldo.