Enhancing energy transition efficiency (ETE) is vital for sustainable development and climate mitigation. This study measures national ETE from 2008 to 2022 using the Super-SBM model and analyzes its spatiotemporal patterns. The GML index is decomposed to isolate the effects of technological progress and technical efficiency changes on ETE. The Spatial Durbin Model (SDM) examines how green finance and high-quality development interact across regions. Results show that the national average ETE increased with fluctuations over the study period, exhibiting a spatial pattern of relatively higher efficiency in the west and lower efficiency in parts of the east and north, mainly driven by large-scale clean energy deployment in western provinces. GML decomposition indicates that ETE growth stems primarily from technological advancement, whereas technical efficiency contributes marginally. HQD shows a significant positive association with ETE, yet its spatial spillover remains weak nationally. Conversely, green finance generates notable negative externalities with pronounced regional heterogeneity; resource competition or policy misalignment may erode efficiency in adjacent areas. These findings underscore the need for coordinated regional green finance strategies and balanced clean energy transition policies.