Abstract: Territorial space pattern and functional evolution are of the practical significance to alleviate the territorial conflicts. This study aims to explore the interactive mechanisms between territorial space pattern and function. Geospatial diagrams and kernel density models were employed to analyze the spatiotemporal features of territorial space pattern and functional evolution in the Yangtze River Economic Belt from 2000 to 2020. Additionally, the bivariate space autocorrelation models were utilized to identify their response to the territorial space pattern and functional evolution. The results indicated: ① The urban space was expanded by 29,559.54 km² in the study area over two decades, leading to the reductions of 25,162.63 and 3,268.36 km² in the agricultural and ecological spaces. The exchange and internal restructure of agricultural and ecological spaces dominated in the evolution of territorial space pattern. The rate of change in the territorial space pattern exhibited a regional differentiation pattern, where the upstream region evolved faster than the middle and downstream. ② The mean values of urban, agricultural, and ecological functions increased from 0.129, 0.287, and 0.646 to 0.343, 0.456, and 0.698, respectively. The territorial space functions in the middle and downstream regions was driven by urban and agricultural functions, while in the upstream region, it was dominated by ecological functions and elevated agricultural functions. There were the regional differences in the intensity of territorial space function, where the downstream region surpassed the middle and the upstream regions. ③ A bidirectional nonlinear relationship was found in the territorial space pattern and functional evolution. Urban space expansion and the functional enlargement showed a positive space correlation characterized by “both increasing.” Conversely, the conflict of agricultural and ecological spaces was negatively correlated with the their functions, indicating a “one decrease, one increase” space pattern. There was the higher level of response in the territorial space pattern and functional evolution in the upstream and downstream regions, but the lower in the middle region. The trend was attribute to the siphon effect of urban and agricultural functions from the upstream region, and the spillover effect of ecological functions from the downstream region. Some recommendations were proposed to focus on enhancing, optimizing, and expanding territorial space functions, in order to promote the sustainable and balanced development of the Yangtze River Economic Belt. A complementary, integrated, and coordinated territorial space pattern can also be achieved in the urban development, agricultural preservation, and ecological restoration.