Diano San Pietro (Ligurian: Dian San Pê) is a comune (municipality) in the Province of Imperia in the Italian region Liguria, located about 90 kilometres (56 mi) southwest of Genoa and about 6 kilometres (4 mi) northeast of Imperia.

Diano San Pietro borders the following municipalities: Diano Arentino, Diano Castello, San Bartolomeo al Mare, Stellanello, and Villa Faraldi.

Diano San Pietro is the setting for the books by the English writer Annie Hawes, Extra Virgin and Ripe for the Picking.