Soil mapping of urban areas is required for solving many applied problems. However, its methodology is still under development. The lack of information about urban soils and the inconsistence of their classifications are the main difficulties, as well as the intricate soil cover patterns in cities and towns. The research was aimed to compile the soil map for the drainage basin of the small urban river Setun at a scale that could reflect its soil cover heterogeneity. Some new approaches to the differentiation of urban and semi-urban soils in accordance with recent ideas on their systematic and land use variants have been proposed. The concept of pedo-urbo-mosaics, which implements the soil cover pattern theory in relation to urbanized territory, has been used for delineating mapping units. The compilation methodology involved the use of open spatial data and GIS technologies. The subdivision of the basin into mapping units was performed using ©OpenStreetMap data and Yandex Maps Web mapping service. Spatial analysis in GIS allowed for mapping the territory with a moderate urbanization rate on a large scale, obtaining a more adequate and detailed spatial representation of the area than in the case of applying the traditional approach. The map, at a scale of 1:60,000 contains 16 natural/semi-natural soils and technogenic superficial formations, as well as 11 pedo-urbo-mosaics. The study may be of methodological interest as an experience in soil mapping of urbanized areas using GIS.