Castronuevo de Esgueva is a municipality in the province of Valladolid, within the autonomous community of Castile and León, Spain. It lies in the central part of the country, in the region traditionally associated with the Esgueva river valley, from which the locality takes part of its name.
According to the 2004 census carried out by the Instituto Nacional de Estadística (INE), the municipality had a population of 337 inhabitants. This figure reflects the small, rural character typical of many municipalities in the province of Valladolid.
As a Spanish municipality, Castronuevo de Esgueva forms part of the local administrative structure of the province of Valladolid and the wider community of Castile and León.