Extremely polarized space and demographic processes, as well as the most significant concentration of population and functions on the territory of the capital and its surroundings, are the characteristics of the most post-socialist countries. One of those cities is Belgrade, the capital of the Republic of Serbia, on the example of which this research was conducted. At the beginning of the 21st century, urban systems, as observed, are experiencing significant transformations, which represent new trends in their spatial and population development. This paper investigates and analyzes the links between certain spatial-functional and demographic changes within the daily urban system of Belgrade. The model of spatial manifestation of daily labor migration was used to determine the boundaries of the observed area, while census statistics were used as a basic source of data. Changes in the core of the urban system, as well as in the most important satellite settlements and secondary centers, were especially emphasized. Based on the analyzed phenomena, conclusions about the connections and interdependence of contemporary demographic processes and spatial-functional changes within the urban system of the capital, on the example of Belgrade, are presented.