Cubillas de Rueda is a municipality in the province of León, within the autonomous community of Castile and León, Spain. It is located in the northwestern part of the country, in a region characterised by a continental climate and a landscape of plains and low hills typical of the Leonese countryside.
According to the 2010 census conducted by the Instituto Nacional de Estadística (INE), the municipality had a population of 501 inhabitants. As with many rural municipalities in this part of Spain, the population is distributed across the municipal territory, which comprises several small settlements rather than a single large urban centre.
The municipality is one of many small, sparsely populated administrative units that make up the province of León. Its demographic profile reflects broader patterns seen across rural Castile and León, where municipalities of a few hundred residents are common.