The co-evolution of urban–rural spatial transformation and ecosystem services represents a key scientific issue for high-quality basin development and metropolitan ecological governance. As a core growth pole in the lower Yellow River Basin, the Jinan Metropolitan Area (JMA) faces the overlapping pressures of rapid urbanization and ecological constraints, making it an appropriate case for exploring the interactions between the urban–rural gradient and ecosystem service value (ESV). Based on multisource spatiotemporal datasets for 2000–2024, this study deploys a modified equivalent-factor method, a multidimensional urban–rural gradient model, and a geographic detector to investigate ESV dynamics, the evolution of the urban–rural gradient, and their coupling relationship at a 1 km × 1 km grid scale. The results show that: (1) Total ESV in the JMA increased slightly from 2000 to 2024, with pronounced spatial heterogeneity. High-ESV areas were distributed in the southern mountainous region and along the Yellow River, whereas low-ESV areas were mainly distributed across the northern plains and urban built-up areas. Forestland and water bodies provided the primary foundation for regional ESV stability. (2) Inner-suburban areas expanded rapidly and became the dominant urban–rural transition zone, while rural areas continued to contract. Urban areas exhibited both polarization and sprawl along transportation corridors. (3) The coupling coordination between ESV and the urban–rural gradient exhibited a “high-periphery, low-middle” spatial pattern and declined slightly over time. Land-use change, population density and normalized difference vegetation index (NDVI) serve as core driving factors, with nonlinear threshold effects; pairwise factor interactions exert stronger explanatory power than individual factors. This study advances the analytical framework for examining ESV in basin-metropolitan areas and provides a reference for integrated urban–rural development and ecological protection in similar regions.