Archaeological excavations in the Mincio valley include a Bronze Age settlements, some tombs dating to the Iron Age and some findings associated with the Etruscan civilization. A large Celtic necropolis, found in 1984 still partly buried under the current town, would prove the presence of that people from the 4th century AC and the 1st century DC.
The creation of the villages of Valeggio and Borghetto dates to the Lombard rule in northern Italy.
The monastery of Santa Maria was founded here, on the Mincio shore, was founded here in the 12th century; later it was a priory of the Knights Templar.
The large medieval fortifications which characterize Valeggio (Scaliger castle, the Visconti Bridge and the Serraglio difensive line) were built between the 13th and the 14th centuries. In 1405 Valeggio became part of the Republic of Venice, and subsequently lost its strategic role, becoming an agricultural center and a silkworms trading market.
After the fall of the Republic of Venice in 1797, Valeggio was included in the Cisalpine Republic. Later it was part of the Italian Republic (1802-1805) and, after some decades under the Austrian rule, of the newly unified Kingdom of Italy.