In the macro context of global climate change, given the profound challenges that the intensifying greenhouse effect poses to global ecological balance and sustainable economic and social development, the role of foreign direct investment (FDI) is increasingly acknowledged, particularly regarding its dual impact on the environment: while serving as a catalyst for economic growth, it might also exacerbate carbon emissions in host countries. This paper focuses on the panel data of 11 provinces and cities in the western region (excluding Xizang) from 2006 to 2021, calculates the implied carbon of foreign-invested enterprises in the western region, and explores the relationship between the implied carbon of foreign-invested enterprises in the western region and the economic development of the western region. The results indicate that from 2006 to 2021, the implied net carbon value of import and export trade of foreign-invested enterprises in the western region was greater than zero and roughly exhibited an upward trend year by year. FDI has an environmental deficit in terms of carbon emissions in the western region; FDI in the western region has a significant positive effect on the implied carbon emissions in import and export trade; The GDP of the western region has a significant positive effect on the implied carbon emissions of import and export trade. Therefore, this article puts forward corresponding suggestions from five aspects: policy incentives and regulatory constraints, technology research and innovation drive, clean energy development and resource recycling, international cooperation and regional linkage, and public awareness enhancement and cultural advocacy.