Prussian blue analogues (PBA) are a large family of functional materials with diverse applications such as in electrochemical fields. However, their use in the emerging two-electron oxygen reduction reaction for clean production of hydrogen peroxide (H₂O₂) is lagging. Herein, a general solvent exchange induced reconstruction strategy is demonstrated, through which an abnormal NiNi-PBA superstructure is synthesized as a high-performance electrocatalyst for H₂O₂ generation. The resultant NiNi-PBA superstructure has a stoichiometric composition with saturated lattice water, and a leaf-like morphology composed of interconnected small-size nanosheets with identical orientation and predominate {210} side surface exposure. Our studies show that the Ni−N centers on {210} facets are the active sites, and the saturated lattice H₂O favors a six-coordinated environment that results in high selectivity. The “perfect” structure including stoichiometric composition and ideal facet exposure leads to a high selectivity of ~100 % and H₂O₂ yield of 5.7 mol g⁻¹ h⁻¹, superior to the reported MOF-based electrocatalysts and most other electrocatalysts.