Abstract: Under the dual pressures of global climate change and rapid urbanization, river system connectivity is a critical factor for regional water security and urban sustainable development. This study focuses on the highly urbanized Pearl River Delta, utilizing high-resolution remote sensing imagery to extract water body data. We construct a comprehensive assessment system for river connectivity, covering both structural and functional aspects (river network density, water surface ratio, circuitry, and node connectivity). By incorporating urban development indicators and applying the Analytic Hierarchy Process-Entropy Weight Method (AHP-EWM) to determine weights, the Coupling Coordination Degree Model (CCDM) is used to quantitatively evaluate the interaction between river system connectivity and urban development in the region for 2024. Key findings show: (1) Significant spatial variation in connectivity, with Foshan, Zhuhai, and Dongguan exhibiting structural advantages; (2) Urban development follows a “dual-core pattern led by Guangzhou and Shenzhen,” aligning with economic levels; (3) Coupling coordination analysis indicates cities like Guangzhou, Foshan, and Dongguan are at an “intermediate coordination” stage, while peripheral cities such as Jiangmen, Zhaoqing, and Huizhou are in an “imbalanced decline” state. This research reveals the intrinsic feedback mechanisms between river systems and urban functions in rapidly urbanizing areas, providing scientific support for spatial planning, water ecological security, and harmonious human-water development in the Pearl River Delta.