The article examines demographic processes in the transboundary regions (the Russian-Kazakh border area) of Russia and Kazakhstan, which, despite their strategic importance, often remain on the periphery of national policy. The methodological framework is based on a proposed three-level approach (national, regional, local), enabling the identification of both macro-demographic trends and intraregional differentiation. The analysis of statistical data for the period 1989–2021 reveals that the key challenges for the borderlands include natural population decline, persistent migration outflow, and increasing spatial polarization. A significant asymmetry in demographic development has been identified: Kazakh regions exhibit more pronounced depopulation, while the Russian border areas maintain relative stability, retaining their migration attractiveness. At the local level, a general centripetal trend is confirmed – concentration of population in regional centers and depopulation of rural peripheries. The study’s results underscore the need for developing a coordinated bilateral policy aimed at stimulating economic development, improving the quality of life in border regions, and supporting nodal cities and agglomerations capable of becoming centers of demographic and economic attraction.