Garnet-type solid-state electrolytes Li 7 La 3 Zr 2 O 12 (LLZO) for high-energy-density batteries have attracted extensive attention. However, stabilizing the high-conductive cubic phase and improving its ionic conductivity remain challenges of current research. Here, a Ca−W dual-substitution strategy has been designed, and the effect of doping on cubic phase formation and Li + mobility has been investigated thoroughly. The results indicated that the partial substitution of Ca 2+ at the La 3+ site and W 6+ at the Zr 4+ site can effectively stabilize the cubic phase while reducing the endothermic enthalpy during the synthesis. Moreover, Ca−W dual substitution regulates the local Li + framework by increasing Li + occupancy at the 96h site, which can significantly lower the Li + migration barrier and thus improve the ionic conductivity by two orders of magnitude. This work addresses the challenge of stabilizing a highly conductive cubic phase with low-energy consumption and represents a major breakthrough in understanding how to improve the ionic conductivity by regulating local structures.