Variations in land use and land cover (LULC) patterns are the principal driving factors affecting the ecosystem service value (ESV). Quantitatively exploring ESV variations is crucial for achieving sustainable development in typical regions. The uncontrolled area in the middle and lower reaches of the Yellow River (UAMLYR) is highly vulnerable to precipitation impacts, subsequently influencing the ESV of this area, in view of the absence of reservoirs for water interception and storage. Based on the LULC data from 1990, 2000, 2010, and 2020, the variations in LULC were analyzed using a LULC transition matrix. The driving factors of ESV spatial differentiation and their response to LULC variations were studied via the improved equivalent factor method, geographical detector, and Pearson correlation analysis. The patch-generating land use simulation (PLUS) model was employed to emulate the spatiotemporal evolution of LULC and ESV under four scenarios. The results indicate that farmland is a major LULC type in the research field, serving as the primary source for transitions to other LULC, with construction land being the type with the largest area of inflow. ESV in the region showed a downward trend from 1990 to 2020, and under four scenarios in 2030, the ESV was higher than that in 2020. Ecological conservation scenarios increased total ESV dramatically, while town development scenarios were more beneficial to the urbanization process. Soil erosion has the greatest impact on ESV, and human activities further enhance the impact on ESV. These research findings contribute to the construction of a new pattern of territorial spatial development and protection in the region and provide relevant references and theoretical foundations for ecosystem research in other similar regions around the world.