Abstract: The Yellow River Basin (YRB) is rich in mineral resources and is known as China’s “energy basin”. Under the background of carbon peak and carbon neutrality, the low-carbon transformation of mining agglomeration is the key to the ecological protection and high-quality development of the YRB. Based on the panel data of 90 prefecture-level administrative regions in the YRB from 2003 to 2018, this paper constructed a spatial mediating effect model to explore the impact mechanism of mining agglomeration on urban carbon balance from the perspective of spatial spillover. The results show that: (1) mining agglomeration significantly worsens the carbon balance of the mining city itself, but improves the carbon balance of the surrounding cities to a certain extent, indicating that the “carbon curse” hypothesis is true in the YRB, and mining agglomeration areas suffer the obvious environmental inequities, such as energy and resource export, carbon emissions, and ecological damage retention. (2) Mining agglomeration significantly worsens the carbon balance of mining agglomeration cities through three intermediary paths: hindering industrial upgrading, inhibiting technological progress and reducing land carbon sequestration capacity. Industrial upgrading has the largest mediating effect, which is the key low-carbon transformation path of mining agglomeration areas. (3) There is significant spatial and temporal heterogeneity in the impact of mining agglomeration on urban carbon balance in the YRB. The impact intensity and transmission path are different in the boom and transition periods and between different reaches. In response to the research conclusion, it is believed that attention should be paid to the problem of environmental inequality between mining agglomeration areas and non-mining agglomeration areas. Through transfer payments and scientific allocation of emission reduction responsibilities, mining agglomeration areas should bear the “common but differentiated” emission reduction responsibilities. Multiple methods such as industrial upgrading, technological progress, and improving land carbon sequestration capacity should be taken to break and prevent the “carbon curse” based on time and local conditions. This research aims to provide theoretical support for mining agglomeration areas to undertake “common but differentiated” emission reduction responsibilities and clarify low-carbon transformation paths.