Urban physical expansion and land-use changes are major consequences of urbanization, potentially leading to natural land loss, changes in urban spatial structure, and the degradation of ecological functions. Tehran’s river-valleys, as important spatial, ecological, and identity-bearing elements, have also been affected by urban expansion and land-use changes. This study comparatively analyzes land-use and land-cover changes in metropolitan Tehran and its river-valleys from 1972 to 2026. The research is theoretical–applied in purpose, descriptive–analytical in nature, and quantitative in approach. Landsat satellite images from seven time points were classified in ENVI using supervised classification and the Support Vector Machine (SVM) algorithm, and the results were analyzed in a Geographic Information System (GIS). The findings indicate that the dominant trends in both study areas were the expansion of built-up areas and the decline of barren lands. During the study period, built-up areas increased by 250% in metropolitan Tehran and 259% in the river-valleys, while barren lands decreased substantially. Tehran’s land-use changes can be characterized by three stages: rapid physical expansion, very intensive growth, and slower but denser and more complex development. Green spaces in Tehran increased during the earlier periods but declined from the 2000s onward. In contrast, despite fluctuations and periodic decreases, the total green-space area in the river-valleys increased slightly over the study period. These findings show that although the river-valleys have been influenced by broader urban development trends, they exhibit a distinct pattern of land-use change. Protecting natural and green lands, controlling construction and land-use changes, and strengthening ecological connectivity and public access to the river-valleys are therefore important considerations for urban planning and policy.