The decarbonization of the fossil fuel-intensive power sector is critical for climate mitigation. During the global financial crisis, we found that major countries changed their energy inputs and achieved a rapid low-carbon transition in the global power sector. In this study, we employ two-stage decomposition models to reveal the diverse drivers of the peak-and-decline dynamics in the global CO2 intensity of electricity. We then examine the regional heterogeneous drivers of CO2 intensity from major electricity-producing countries within three income groups. Results show that the global CO2 intensity of electricity reached its peak in 2007 and has declined by 0.35% per year since then. High-income countries consistently reduce the CO2 intensity, while upper- and lower-middle income countries contributed to a reduction of the CO2 intensity until recently. The adoption of renewable energy, the phase-out of thermal power, and improvements in energy efficiency supported by pronounced regional allocation effects contribute to the rapid decline in the global CO2 intensity of electricity. This paper reveals breakthroughs in the recent global energy transition and sheds light on future CO2 mitigation pathways in the global power sector.