Reducing agricultural carbon emissions (ACEs) is critical to achieving green agriculture in China. Chinese agriculture has long faced the dilemma of large numbers of people and small landholdings, as well as low-quality arable land. As a result, agricultural production relies heavily on inputs of agricultural chemicals to boost yields, damaging the rural environment. In this study, we use provincial panel data from China and a spatial difference-in-differences model to explore the influence of rural land consolidation policy (RLCP) on ACEs and their spatial spillover effects. The results show that the global Moran’s I of ACEs reflected a downward trend, the spatial correlation gradually weakened, and ACEs developed from a state of polarization to one of balance. RLCP has had a significant reduction and a negative spatial spillover effect on ACEs. Our analysis of the mechanism shows that rural land consolidation promoted the reduction of ACEs by improving the quality of farmland soil and the utilization rate of water resources. Under different geographical conditions, the construction of rural land consolidation has had a significant ACE reduction effect on both the south and the north, although RLCP in southern China has had a negative spatial spillover effect.