Carbon emissions reduction is crucial to global climate governance and sustainable development. By 2060, China envisioned being carbon-neutral, and it has adopted a series of policies and measures for environmental management, especially in the main stream of Yangtze River basin, where China’s carbon emissions are centered. The spatial distribution characteristics and agglomeration effects of carbon dioxide (CO2) emissions in the main stream of Yangtze River basin are analyzed from 2010 to 2019 based on the perspective of local (city and state) administrative regions, and uses the spatial Durbin model to examine the influencing factors and spatial spillover effects of carbon emissions. The findings discovered from the extensive research are as follows: First, carbon emissions in the main stream of Yangtze River basin present a fluctuating upward trend, and CO2 emissions in the lower reaches are significantly higher than those in the middle and upper reaches, which are closely related to the economic volume. Secondly, carbon emissions have a significant positive spatial correlation among prefecture-level cities, and carbon emissions show a high-high concentration in downstream regions and low-low concentration in upstream regions. Thirdly, regional economic development level, secondary industry development level, and population density have considerable influence on CO2 emissions, among which the Kuznets hypothesis is evidenced by the interaction between economic progress and carbon emissions. Therefore, strengthening regional cooperation efforts and collaborating to promote low-carbon development are the vital ways to achieve carbon emissions reduction.