The limited nature of land supply determines that improving land use efficiency is an inherent requirement for economic development. The aim of this study was to quantitatively examine its impact. Most current studies have explored the quantitative relationship between urban land use efficiency (ULUE) and economic development, but less attention has been given to the mechanism of action of both. In this study, we construct an analysis framework for the mechanism of ULUE in promoting economic development from three aspects: economic scale, economic structure, and economic quality, and we quantitatively investigate its impact on economic development and intermediate action mechanism through a mediating effect model on the basis of measuring ULUE by using a super-efficiency SBM-undesirable model. Based on the analysis of the panel data of 56 cities in the Yellow River Basin (YRB), the results show that, first, ULUE has formed an ideal positive driving effect on economic development, and its influence mechanism has obvious heterogeneity in cities with different geographical locations and resource endowments. Second, ULUE affects economic development through three channels: economic scale-up effect, economic structure optimization effect, and economic quality enhancement effect, and there are two different mechanisms of mediating effect and suppressing effect. Finally, variables such as investment intensity of urban construction land and social benefit act as suppressing effects, while variables such as economic output density of urban land, industrial structure, employment structure, economic benefit, and environmental benefit play partial mediating effects. These evidence-based findings can provide practical guidance for solving the dilemma of a lack of economic development momentum and inefficient land use in a country or region.