Aqueous rechargeable batteries (ARBs) represent one of the most promising solutions for stationary energy storage, owing to their intrinsic low cost, high safety and environmental friendliness. To date, most attention has been paid to metal cations as charge carriers, such as Li⁺, Na⁺, K⁺, Mg²⁺, Zn²⁺ etc.; however, non-metal cations like hydronium (H₃O⁺) and ammonium (NH₄⁺) ions received rare attention from the battery community. In this work, we revealed the unique intercalation chemistry of NH₄⁺ ions in Prussian blue analogues (PBAs), and proposed a “rocking-chair” NH₄⁺-ion battery in full cell configuration. Comparative studies showed that Berlin green Fe[Fe(CN)₆] lattice could demonstrate the highest reaction potential, lowest structural strain and best cycling performance for NH₄⁺ intercalation than Na⁺ and K⁺ ions. We then prepared an ammonium-containing Prussian white analogue, (NH₄)₂Ni[Fe(CN)₆], by a facile ion-exchange method. When coupled with an organic solid, perylenetetracarboxylic diimide (PTCDI), this aqueous NH₄⁺-ion full cell can deliver a working voltage of ~1.0 V, an energy density of ~43 Wh kg^-1 and impressive cycling performance of 1000 cycles. These results may open a new avenue for NH₄⁺-based energy storage applications.