How to accelerate the reduction of carbon emissions in the context of the “double carbon” target has become a key concern for all sectors of society. This paper firstly analyzes the influence mechanism of foreign direct investment (FDI) agglomeration on carbon emission intensity, from a theoretical perspective. Then, based on a panel data of 270 cities in China from 2006 to 2019, this paper uses ArcGIS software to visually analyze the spatial and temporal characteristics of FDI agglomeration and carbon emission intensity, and constructs traditional fixed effect models and spatial econometric models for empirical analysis. The results show that, first, FDI agglomeration has a significantly positive impact on the carbon emission intensity of local and neighboring cities with crowding effect. Second, the level of technological innovation can mitigate the crowding effect of FDI agglomeration on carbon emission intensity in local and neighboring cities. Third, there is a negative spatial autocorrelation between the local carbon emission intensity and the carbon emission intensity of neighboring cities. Fourth, the crowding effect of FDI agglomeration on carbon emission intensity is mainly concentrated in the central and western regions. Based on the research conclusions, this paper puts forward corresponding countermeasure suggestions.