The inherent thermodynamic instability of FeO42− in water restricts its applications in water treatment, battery, and organic synthesis. The objective of this paper was to research and develop an additive for stabilization and mechanism of aqueous FeO42− solution on the basis of a choice of the redox equilibration. In this study, it was found that FeO42− in water was stabilized by the right match and adoption of KIO4 called an equalizer. The redox thermodynamic analysis and dynamic experimental results show that the adoption of KIO4 equalizer greatly increased lifetime of FeO42− in water by orders of magnitude. The stabilization mechanism is attributed to occur via the effect of redox equilibrium of the FeO42− and the IO4− species, as well as the formation of an oxidizing chemical environment. This study opens up possibilities for stabilization of solid ferrate compounds, for example, for use in the water treatment and super-iron battery.