The article provides a comprehensive analysis of the prerequisites for the emergence, legal foundations, and functional characteristics of the institution of sultan-rulers established in the territory of the Junior Zhuz between 1824 and 1869. The study aims to reveal the essence of the abolition of khanate authority and the introduction of new administrative structures within the process of implementing the colonial governance system of the Russian Empire. Based on archival sources, the research examines the procedures for awarding military ranks to Kazakh sultans under the colonial policy of the Russian Empire, their step-by-step promotion, the hereditary nature of ranks, and their incorporation into the imperial nobility. The author analyzes the implementation of administrative-territorial division in the Junior Zhuz, the social status of sultan-rulers, their material provision, as well as the significance of military ranks and symbols of authority. Furthermore, the administrative, judicial, and political functions of sultan-rulers, their interaction with the Orenburg administration, and their role in carrying out assignments of the tsarist government are identified. The study concludes that the institution of sultan-rulers had a significant impact on the transformation of the traditional power system in Kazakh society, processes of social stratification, and changes in relations between authorities and the population. The article contributes to the study of the nineteenth-century colonial history of Kazakhstan and to the introduction of archival materials related to the institution of sultan-rulers into scholarly circulation.