Agricultural carbon emission has been one of the major sources of greenhouse gases in China. In this sense, the exploration of carbon emissions reduction in agriculture has become a core issue in the process of China' agricultural green transformations. Farmers' specialized cooperatives are a key organization bridging smallholder farmers and modern agriculture, and the influence of its development on carbon emission reduction is a noteworthy question. In the context of the dual-carbon strategy, this paper, based on the panel data of 30 provinces spanning 2013 to 2023, builds a two-way fixed effect model and a moderating-effect model to empirically test the impact of farmers' specialized cooperatives on agricultural carbon emissions and the mechanism behind it. The research finds that farmers' specialized cooperatives have an inhibitory effect on agricultural carbon emissions, and the conclusion is still valid after a series of robustness tests. It is also found that the intensity of financial support for agriculture will weaken the inhibitory effect of farmers' specialized cooperatives on agricultural carbon emissions, thus having a negative regulatory effect. Besides, regional heterogeneity shows that the emission reduction effect of cooperatives is significant in non-major grain-producing areas, and the eastern and western regions, but it fails in the significance test in major grain-producing areas and the central regions. Accordingly, this paper proposes some suggestions to optimize the green-transformation pathway for farmers' specialized cooperatives, to adjust the fiscal-support policy for agriculture, and to implement differentiated regional governance. In this vein, this paper expects to provide a decision-making basis for reducing agricultural carbon emission and promoting high-quality agricultural development.