This article is an attempt to analyze the reasons for the creation of the Eparchy (diocese) of Omsk in 1895, with the synodal decree being issued and signed. The stated problem is urgent, since in this period of time the annexation of the Southern Kazakhstan territory to the Russian Empire completed, and the administrative-territorial unit system of West Siberia was formed. Russian Orthodox Church, one of the main political institutions of the state, played an important role in the spiritual aspect of the control system in the region and the process of Russification there. Therefore, a new administrativeterritorial structure of the Russian Orthodox Church consistent with the provincial administrative and territorial structure was formed by the end of the 19th century in West Siberia. In this regard, the identification of the causes which led to a new church unity appearing on the map of West Siberia in the late 19th century is of great scientific interest. Based on the analysis of a wide range of documents and literature, the author identifies a number of reasons for this historic event. According to the researcher, the most significant was the process of making the Central Asian borders of the Russian Empire and the formation of the Governor-generalship of the Steppes. This new administrative-territorial unit demanded its inclusion in the scope of activities of the Russian Orthodox Church. Another important reason for the formation of the Eparchy of Omsk was peasant colonization of the Kazakh steppe, which began in the late 19th century. This led to a sharp increase in the number of the Orthodox population of the region. Among other causes are ethnic and religious heterogeneity of the steppe, and the need to spread the influence of the Russian Orthodox Church among the Old Believers, sectarian and Muslim population.