A sulfur-containing zwitter-molecule, methionine (Met), is used as an additive in ZnSO₄ electrolytes to enhance the performance of aqueous zinc metal batteries (AZMBs). In the electrolyte, Met reduces the coordination number of H₂O, facilitates desolvation, and accelerates Zn²+ transference kinetics by functional groups such as -COOH, -NH₂, and C-S-C. On the Zn anode, Met preferentially adsorbs on the Zn(002) plane and oxidizes to form a zincophilic protective layer containing C-SOx-C, suppressing H₂ evolution and corrosion reactions and guiding dendrite-free Zn deposition. Met-ZSO electrolytes enable superior cycling performance in Zn//Zn and Zn//NH₄V₄O₁₀ full cells under various conditions, including extreme temperatures (-8 to 60 °C) and high current densities. Met-ZSO also achieves a high energy density of 105.30 W h kg⁻¹ with a low N/P ratio of 1.2, showing promising practical applications. The study reveals that Met modifies the Zn anode by synergistically suppressing HER/corrosion reactions and guiding dendrite-free Zn deposition. DFT and MD simulations show that Met interacts with Zn²+ and H₂O, reorganizes the Zn²+ solvation structure, and reduces H₂O activity. Met forms a protective layer on the Zn anode, inhibiting corrosion and improving Zn²+ transference. The Met-derived SEI layer has higher Zn²+ transference numbers and zincophilic properties, enhancing Zn plating/stripping performance. Met-ZSO enables dendrite-free Zn deposition, suppresses HER, and provides excellent cycling performance in wide temperature ranges. The study demonstrates the effectiveness of Met as an electrolyte additive for AZMBs, offering a new strategy for improving Zn anode performance and practical applications.A sulfur-containing zwitter-molecule, methionine (Met), is used as an additive in ZnSO₄ electrolytes to enhance the performance of aqueous zinc metal batteries (AZMBs). In the electrolyte, Met reduces the coordination number of H₂O, facilitates desolvation, and accelerates Zn²+ transference kinetics by functional groups such as -COOH, -NH₂, and C-S-C. On the Zn anode, Met preferentially adsorbs on the Zn(002) plane and oxidizes to form a zincophilic protective layer containing C-SOx-C, suppressing H₂ evolution and corrosion reactions and guiding dendrite-free Zn deposition. Met-ZSO electrolytes enable superior cycling performance in Zn//Zn and Zn//NH₄V₄O₁₀ full cells under various conditions, including extreme temperatures (-8 to 60 °C) and high current densities. Met-ZSO also achieves a high energy density of 105.30 W h kg⁻¹ with a low N/P ratio of 1.2, showing promising practical applications. The study reveals that Met modifies the Zn anode by synergistically suppressing HER/corrosion reactions and guiding dendrite-free Zn deposition. DFT and MD simulations show that Met interacts with Zn²+ and H₂O, reorganizes the Zn²+ solvation structure, and reduces H₂O activity. Met forms a protective layer on the Zn anode, inhibiting corrosion and improving Zn²+ transference. The Met-derived SEI layer has higher Zn²+ transference numbers and zincophilic properties, enhancing Zn plating/stripping performance. Met-ZSO enables dendrite-free Zn deposition, suppresses HER, and provides excellent cycling performance in wide temperature ranges. The study demonstrates the effectiveness of Met as an electrolyte additive for AZMBs, offering a new strategy for improving Zn anode performance and practical applications.