The imbalance between the supply and demand of urban ecosystem services significantly impacts land resource utilization and residents’ quality of life. This study innovatively examines the spatio-temporal evolution of these services at the block scale in Xiamen, China, from 2012 to 2022, addressing a gap in current research that often focuses on larger scales like watersheds. Using multi-source data, six ecosystem services, including water conservation, carbon sequestration, and habitat quality, were assessed, revealing notable deficiencies. The study also employs the GMOP-PLUS model to simulate land use and ecosystem service changes under three scenarios—Natural development (ND), Economic development (ED), and Ecological low-carbon development (EL)—projected to 2027. Results highlight a significant spatial imbalance with a “North Supply, South Demand” pattern, particularly in southern urban areas. While all scenarios show a decline in green space and ecosystem services, the economic growth scenario improves economic benefits, and the ecological conservation scenario enhances low-carbon and ecological services. This research provides novel insights and optimization strategies for urban land use planning, aiming to enhance ecosystem services and support sustainable urban development.