<p>Rapid and dynamic urbanization encourages land use/land cover (LULC) change that threatens ecological quality and carbon emissions. However, spatial–temporal research on the impact of urbanization on carbon emissions and ecological quality is limited, particularly spatial distance-based analysis from urban to peri-urban areas. This study aims to explore the spatiotemporal effect of urbanization on carbon emission and ecological quality of the Semarang Metropolitan Region to support sustainable development. We used Landsat 7 ETM + (2003) and Landsat 8 OLI (2023) images. The analyses used were the stock-difference method and the Remote Sensing Ecological Index (RSEI). To calculate carbon emissions, we used land cover data, land use changes, and emission factors. As for the RSEI, we used the Tasseled Cap Wetness (TCW), Normalized Difference Vegetation Index (NDVI), Index-Based Built-Up Index (IBI), and Land Surface Temperature (LST). The results show a low positive correlation between urbanization and carbon emissions (<i>R</i> = 0.24). However, urbanization had a strong negative correlation with ecological quality (<i>R</i> =  − 0.62), indicated by a significant decline in ecological quality in urban areas. The spatial correlation between ecological quality and carbon emissions was also highly negative (<i>R</i> =  − 0.603). In other words, the higher the emissions, the lower the ecological quality. If this situation continues, the community’s quality of life will decrease, and the government’s incurred costs to repair the damage will be excessive. This study finally recommends the need for a spatial policy to control the growth of integrated cities as a mitigation effort against the impacts of urbanization to minimize environmental degradation and achieve carbon neutralization.</p>