• Host–guest inversion engineering creates a novel 'polymer guest-in-ceramic host' architecture (PVH-in-SiO2) that optimizes interfacial contacts and comprehensive properties.
• The PVH-in-SiO2 electrolyte achieves an exceptional ionic conductivity of 1.32 × 10−3 S cm−1 at 25 °C with an ultralow residual solvent content of 2.9 wt%.
• LiFePO4|PVH-in-SiO2|Li full cells demonstrate a significant capacity retention of 92.9% at an ultrahigh rate of 3C after 300 cycles at 25 °C.
• The strategy is versatile, extending to Na+ and K+ based PVH-in-SiO2 CSEs, delivering excellent ionic conductivity of 10−4 S cm−1 at 25 °C, outperforming previous reports.