The urban built-up land green use efficiency (UBLGUE) of the Central Plains Urban Agglomeration (CPUA) is greatly affected by the Central China Rise policy. However, studies on how socioeconomic factors affect UBLGUE in underdeveloped urban agglomerations are lacking, and little empirical research has placed particular emphasis on the Central China Rise policy. Based on the statistical data of 2003–2020, this study explores the dynamic spatial–temporal characteristics and determines the influencing mechanism of UBLGUE in the CPUA via the super-SBM–DEA method and panel regression model. The empirical results indicate the following: The average UBLGUE in the prefecture cities of the CPUA presents a significant fluctuating trend from 2003 to 2020. The UBLGUE of the CPUA is characterized by spatial imbalance. Over the period of Central China Rise, the main factors influencing the spatial–temporal differentiation of the UBLGUE in the CPUA are the economic development, industrial structure, environmental regulation intensity, and energy consumption intensity. UBLGUE has strong economic attributes and is positively promoted by economic development. In contrast, the industrial structure, environmental regulation intensity, and energy consumption intensity significantly hinder the UBLGUE. Energy consumption intensity has the strongest negative effect on UBLGUE. Finally, corresponding policy recommendations are proposed to promote UBLGUE based on the conclusions obtained.