Montechiaro d'Acqui borders the following municipalities: Cartosio, Castelletto d'Erro, Denice, Malvicino, Mombaldone, Ponti, and Spigno Monferrato.

The oldest trace of settlements in the area were found in the surroundings of the Pieve del Cauro (7th century), an old parish church under the influence of the Monastery of Saint Quintino of Spigno Monferrato, now in ruins just outside the hamlet Piana.

In the 11-13th centuries, due to the increase of trade along the ridge route between the Po valley and the Ligurian Sea and the need to provide a better military defence, the current medieval village of Montechiaro Alto (Mons Cauri) was built.

Then ruled by the Duchy of Milan, after the death of Filippo Maria Visconti (1447) Montechiaro was occupied by the armies of Francesco Sforza.

New trades and sales led to the rule of the Marquis of Canelli, the Scarampi-Crivello, the Cavoretti of Belvedere and the Gianazzo of Pamparato, which maintained the feud even after the oath of allegiance to the House of Savoy (1736).