Urban expansion has reshaped land-use patterns, altered the provision of ecosystem services, and brought challenges to regional sustainable development. However, studies on urban agglomerations with uneven development remain insufficient. This study takes the core development area of the Central Plains Urban Agglomeration as the study area and explores changes in ecosystem services during multidimensional urbanization from 2000 to 2020. Using the CASA and InVEST models, three ecosystem services, namely net primary productivity (NPP), water yield (WY), and soil conservation (SC), were quantified. Spatial associations and local heterogeneity were analyzed using the bivariate Moran’s I. The results show that regional urbanization exhibited a Zhengzhou-centered monocentric pattern, with rapid growth in GDP density and significant expansion of urban land. The responses of ecosystem services to urbanization showed divergent trends, with NPP increasing slightly, while WY and SC decreased. NPP and SC showed a synergistic effect, whereas WY had trade-off relationships with both services. Due to uneven regional development, urbanization indicators and ecosystem services showed evident spatially heterogeneous relationships. This study provides evidence for ecological conservation, ecosystem-service management, and sustainable spatial governance in developing urban agglomerations where rapid growth and ecological constraints coexist.