Castelnuovo Berardenga is a comune, or municipality, located in the province of Siena within the Tuscany region of Italy. It is situated approximately 50 kilometres (31 mi) southeast of Florence and about 14 kilometres (9 mi) east of Siena.
The area has been officially included in the Chianti wine-production region since 1932, making it a recognized part of Italy's notable viticulture landscape.