As information and communication technologies gain prominence in rural areas, rural e-commerce has emerged as a crucial mechanism for fostering agricultural and rural development. While the economic impact of rural e-commerce is widely studied, its effects on carbon emissions remain underexplored. Utilizing a multi-period DID model and Chinese county-level panel data from 2011 to 2017, this paper examines the impact of rural e-commerce on carbon emission reduction, employing the "comprehensive demonstration of e-commerce into villages" policy introduced by the Chinese government in 2014 as a quasi-natural experiment. Our findings show that e-commerce demonstration counties experienced a 10.6% reduction in carbon emissions compared to the control group, indicating a significant emission reduction effect. Further analysis reveals that rural e-commerce drives carbon reduction through decreased fertilizer usage, altered cropping structures, and enhanced transportation efficiency. Notably, rural e-commerce's emission reduction effect is more pronounced in major grain-producing regions and areas with higher digitalization levels. This study has crucial theoretical and practical implications for achieving carbon emission reduction and sequestration in agriculture and advancing green agricultural development.