Zwitterionic citrulline (Cit) was introduced as an additive into a 2 mol/L ZnSO₄ electrolyte. Cit molecules preferentially adsorb onto the Zn²⁺ surface, displacing reactive water molecules within the Zn²⁺ solvation sheath, thereby optimizing the Zn²⁺ solvation structure. Simultaneously, Cit coordinates with Zn²⁺ to form a dynamic electrostatic shielding layer, which suppresses the uncontrolled growth of Zn dendrites caused by localized high current density. The synergistic effect of Cit not only effectively reduces and suppresses the hydrogen evolution reaction (HER) rate but also significantly enhances the electrochemical performance of aqueous zinc-ion batteries (ZIBs). Test results show that batteries assembled with Cit/ZnSO₄ electrolyte exhibit superior electrochemical properties compared to those using pristine 2 mol/L ZnSO₄. Specifically, the Zn||Cu asymmetric cell with Cit/ZnSO₄ electrolyte achieves a cycle life exceeding 500 cycles at 0.5 mA·cm^-2 and 0.5 mAh·cm^-2. The Zn||Zn symmetric cell maintains stable operation for over 5,000 hours at 1.0 mA·cm^-2 and 1.0 mAh·cm^-2, and even under harsh conditions of 5.0 mA·cm^-2 and 5.0 mAh·cm^-2, it sustains 2,500 h of cycling. Furthermore, the Zn||V₂O₅ full cell retains high-capacity retention after 1,000 cycles by 1.0 A·g^-1. This work provides novel insights into the development of efficient electrolyte additives and highlights the practical potential of Cit for high-performance ZIBs.