Abstract: Greening of agriculture is related to the transformation and upgradation of modern agriculture, and it is important for high-quality sustainable development. In this study, the Yangtze River Economic Belt, a typical demonstration zone for agricultural green development in China, was used as the research object. Based on panel data from 2001 to 2021, the entropy method, kernel density estimation, Moran’s index test, and geographic detector methods were used to evaluate the quality and spatial-temporal evolution characteristics of agricultural green development in the Yangtze River Economic Belt and identify the key driving factors. The findings are as follows. 1) Agricultural green development in the Yangtze River Economic Belt showed a stable and improving pattern, but the regional gap has increased. 2) Agricultural green development in the Yangtze River Economic Belt has a positive overall spatial correlation and a high degree of agglomeration, and the local agglomeration modes consist mainly of high-high, low-high, and low-low clusters. 3) Social, policy, and economic factors are the core driving factors affecting the spatial-temporal differentiation of agricultural green development in the Yangtze River Economic Belt. The contribution levels of the sub-indices are in the order of population density, per capita GDP, urbanization level, fiscal support policy for agriculture, and industrialization level, but the interaction of the indicators has a stronger impact. To promote the development of upstream agricultural green industry according to local conditions, especially in Guizhou, Yunnan, and other lagging areas with more mountainous and forest land, full play needs to be given to the demonstration and leading role of downstream superior provinces in agricultural green development, and their spatial spillover effect needs to be strengthened. In addition, the interaction between policy support and economic incentives need to be put to full use to promote the expansion of new quality agricultural productivity in the field of green and sustainable development.