Aqueous zinc-ion batteries (ZIBs) are potential candidates for achieving considerable energy savings owing to their environmental benignity and low cost. At present, however, Mn²⁺ dissolution causes structural failure in manganese-based cathodes. Therefore, addressing this issue is vital for improving their cycling stability and specific capacity. Herein, ε-MnO₂ was obtained by annealing MnCO₃ at 350 °C. Subsequently, ε-MnO₂ was coated with a carbon layer (carbonizing D-glucose) to obtain ε-MnO₂@C, which effectively mitigated the Mn²⁺ dissolution as well as the side reactions between the electrode and electrolyte. Electrochemical results revealed a significant improvement in the specific capacity (280 mAh g⁻¹ at 0.2 A g⁻¹) and capacity retention (∼91% over 1700 cycles at 1 A g⁻¹) of the ε-MnO₂@C cathode.