With the advent of globalization, regional integration has been considered an important strategy for national and sub-national governments. However, the increased regionally spatial interaction is accompanied by active human, logistic, and information flows, which introduce risks to regionally ecological land. Hence, proper impact assessments of regional interaction on ecological land, reasonable land use and zoning practices, and protection of land-based resources are necessary to ensure regionally ecological security. The Yangtze River Delta (YRD) has one of the highest levels of socio-economic development and regional integration in China. However, with rapid urbanization and industrialization, the local ecology is threatened by evident scale reduction, landscape pattern fragmentation, and ecological degradation. Studies on the influences of ecological land evolution have mostly focused on urban demographic, social, and economic factors, while less consideration has been given to the spatial interaction of cities in the context of regional integration. On the one hand, the advancement of regional integration brings resource integration and improves the overall competitiveness of the region while promoting the active flow of factors. On the other hand, the concentration of population and industries, improvement of public infrastructure networks, and optimization of industrial structures also bring risks and pressure to the regionally ecological land. This emphasizes the need to explore the spatial and temporal evolution of characteristics and influences of ecological land in the context of regional integration to balance the relationship between regional development and ecological protection, formulate reasonably ecological land protection strategies, and achieve the coordinated and sustainable regional development. This study firstly analyzed the spatiotemporal evolution of ecological land in the YRD. To explain the effect of regional integration and provide implications and suggestions for regional ecological land use management and protection, two geographically weighted regression (GWR) models were constructed separately. One model for the experimental group considered the regional integration factors, while the control group did not consider these factors. The results were then used to compare and analyze the impact of regional integration on the evolution of ecological land in the Yangtze River Delta region. The analysis of the results showed four salient points:(1) from 2000 to 2020, the scale of ecological land in the YRD shrank significantly by 166.56×10⁴ hm², concentrated in 2015-2020. (2) The spatiotemporal evolution of ecological land reduction in the YRD tended to spread from Shanghai, southern Jiangsu, and northern Zhejiang to the surrounding areas. The spreading direction covered all areas of the YRD, while the area of concentrated rapidly ecological land reduction was mainly in northern central Anhui and northern Jiangsu. (3) The analysis results demonstrated that the regional integration had a significant contribution to the evolution of ecological land, and its intensity and scope of action increased over time. Lastly, (4) according to the influence mechanism of ecological land evolution, the types of ecological land evolution in the YRD could be divided into endogenous-driven, exogenous-driven, and development-monitoring types, which can provide decision support for balancing territorially spatial development and ecological land conservation.