Amid intensifying geopolitical fragmentation, growing energy security uncertainty, and increasingly complex external constraints on low-carbon transformation, advancing urban energy transition (UET) through the coordination of multiple environmental regulations has become a critical issue in green development. This study exploits the overlapping implementation of the Low-Carbon City Pilot policy and the Carbon Emissions Trading Pilot policy as a quasi-natural experiment. Drawing on panel data for 283 Chinese cities from 2006 to 2024 and a comprehensive UET index, we employ a multi-period difference-in-differences model to identify the effect of the dual-pilot policies (DPPs) on UET. The results show that the DPPs significantly promote UET, and this finding remains robust across a series of robustness checks. Mechanism analyses indicate that the policy effect operates primarily through improved resource allocation and innovation upgrading, with both channels becoming more pronounced in cities facing higher geopolitical risk exposure. Further analysis shows that the DPPs have stronger effects in non-resource-based, non-old-industrial, non-transportation hub, and weakly regulated cities. In addition, geopolitical risk, industrial foundations, and innovation talent reserves shape the extent to which the DPPs are translated into actual transition performance. We also find that, while the DPPs improve the energy transition performance of pilot cities, they generate negative spatial spillover effects in neighboring areas, manifested in industrial relocation, higher industrial electricity consumption, and greater pollution emission pressure. Overall, the synergy among multiple environmental regulations improves UET, but its effects are context-dependent and may involve spatial reallocation. Stronger policy coordination and regional governance are therefore needed to enhance the resilience of UET.