Optimizing cross-regional energy dispatch is crucial for addressing regional energy resource imbalances and significantly enhancing energy utilization efficiency. This study aims to analyze the potential impact of China’s ultra-high-voltage (UHV) construction on firms’ total factor energy efficiency and provide empirical evidence supporting the role of cross-regional energy dispatch in improving firms’ energy efficiency. The construction of UHV infrastructure has become a vital part of China’s “New Infrastructure” projects, presenting a “Chinese solution” to the global challenge of regional energy resource mismatches. This study employs an enhanced two-step stochastic frontier method to quantify firms’ total factor energy efficiency and utilizes a difference-in-differences model to evaluate the impact of inter-regional electricity dispatch on this efficiency. The empirical analysis results indicate that UHV construction projects increase the total factor energy efficiency of regional firms by an average of 0.45%, which significantly contributes to firms’ total factor productivity. This conclusion remains valid after a series of robustness tests. Furthermore, the heterogeneity analysis results indicate that the UHV construction project increases the total factor energy efficiency of non-energy-intensive industries by 0.49%, and significantly enhances the total factor energy efficiency of the manufacturing industry by 0.94%. However, it has no significant effect on energy-intensive industries or non-manufacturing enterprises. Additionally, the mechanism analysis shows that UHV construction projects affect total factor energy efficiency through three pathways: industrial structure adjustment, urban innovation, and clean energy transition. This study offers insights for addressing regional energy spatial mismatches and provides policy recommendations for developing a new energy system aligned with regional needs.