Agriculture is one of the three major industries in China, and its level of development occupies an important position in the development of the national economy. At present, China vigorously promotes the strategy of rural revitalization, which provides new opportunities for agricultural modernization. Since modern agriculture and regional economy are coupled in a mutually influencing and constraining relationship, this paper constructs a coupled and coordinated evaluation index system of agricultural modernization and regional economic development. Using the entropy value method and coupled coordination degree model, the comprehensive development level and coordinated development degree of agricultural modernization and regional economic development of 31 provinces, autonomous regions, and cities in China from 2011 to 2020 were evaluated, revealing the time evolution and spatial distribution characteristics of the two systems. The results show that: (1) In the past decade, China’s agricultural modernization and regional economy have made some progress in terms of their respective development levels and the degree of coupling and coordination between them. (2) In terms of spatial evolution, there are obvious regional differences between the two systems, and the coupling coordination degree shows a “ladder” distribution pattern from the east to the central, northeastern, and western parts of the country. (3) Regions with a high level of regional economic development also have a relatively high degree of coupling and coordination between agricultural modernization and regional economic development. Our results provide insights into the economic effects of agricultural modernization in China and provide useful insights into the future direction of agricultural development programs in countries around the world.