Electride possesses electrons localized at interstitial sites without attractingnuclei. It brings outstanding material properties not only originating from itsown loosely bounded characteristics but also serving as a quasiatom, whicheven chemically interacts with other elemental ions. In elemental metals,electride transitions have been reported in alkali metals where valenceelectrons can easily gain enough kinetic energy to escape nuclei. However,there are few studies on transition metals. Especially iron, the key element ofhuman technology and geophysics, has not been studied in respect ofelectride formation. In this study, it is demonstrated that electride formationdrives the superionic state in iron hydride under high-pressure conditions ofthe earth’s inner core. The electride stabilizes the iron lattice and provides apathway for hydrogen diffusion by severing the direct interaction between themetal and the volatile element. The coupling between lattice stability andsuperionicity is triggered near 100 GPa and enhanced at higher pressures. Itis shown that the electride-driven superionicity can also be generalized formetal electrides and other rocky planetary cores by providing a fundamentalinteraction between the electride of the parent metal and doped lightelements.