The research is devoted to the process of suburbanization on the example the Irkutsk city agglomeration. The suburbanization is one of the stages of agglomeration development. Mapping and geoinformation methods are particularly important in the our study. They provide extensive opportunities for complex operational mapping and analysis of the suburbanization, in determining its current boundaries and development directions in the Irkutsk agglomeration. We have created a series of maps showing various aspects of the study area (population change, transport accessibility, development dynamics of buildings, air pollution, soil contamination, maps of accessibility of socio-economic infrastructure, etc.). Many of them are not presented in the article due to limited volume. As a result of the study, the specifics of the development of the Irkutsk suburb were noted and the main factors of its development were determined. Transport accessibility is one of the main factors in the formation of a network of suburban settlements. This research has a great scientific and practical significance for science and management structures.