Comarca del Arlanza is a comarca located south-east of the province of Burgos in the autonomous community of Castile and León. It is bounded on the north by the Odra-Pisuerga and the Alfoz de Burgos, south by the Ribera del Duero, on the east by the province of Palencia and west by the Sierra de la Demanda.

In Spain, a comarca is either a traditional territorial division without any formal basis, or a group of municipalities, legally defined by an autonomous community for the purpose of providing common local government services. In English, a comarca is equivalent to a district, county, area or zone.