Understanding the interaction between ecosystem services (ESs) and tourism urbanization (TU) is essential for regional development and decision-making in urban agglomerations in the Yellow River Basin (YRB). Evaluating the coupling coordination degree (CCD) between ESs and TU is vital for regional development in the YRB. This study employs multi-year statistical data and spatial datasets-including land use, digital elevation models, meteorological data, and soil property data-to assess tourism urbanization using the entropy method. Concurrently, ESs, which encompass water yield, soil conservation, habitat quality, and carbon sequestration, are evaluated through the InVEST model. A spatiotemporal analysis of the YRB from 2000 to 2020 reveals two key trends: (1) the spatial polarization of tourism urbanization has intensified, with 68% of high-intensity clusters concentrated in eastern provinces (e.g., Shandong, Henan), sharply contrasting with the underdeveloped western regions (e.g., Qinghai, Ningxia); and (2) the coupling coordination degrees between TU and ESs have declined by 22-35% in ecologically fragile zones, driven by habitat fragmentation and carbon loss. Specifically, water yield and soil conservation have increased by 18% and 24%, respectively, while habitat quality and carbon sequestration have decreased by 14% and 11% in urbanizing areas, reflecting unsustainable trade-offs. The novel contribution of this study lies in establishing a basin-scale CCD framework for urban agglomerations, providing empirical evidence to reconcile tourism-driven growth with ecosystem resilience in the YRB. These findings underscore the urgent need for spatially adaptive governance to mitigate developmental imbalances. Future research should integrate high-resolution data and cultural ESs to address micro-scale complexities.