Aqueous zinc ion batteries (AZIBs) have drawn more notice because of their affordability, high security, and favorable ecological impact. So far, manganese oxide (MnO₂) is thought to be an attractive material for storing energy among cathodes of aqueous zinc ion batteries. In particular, the layered manganese dioxide (δ-MnO₂) is more favorable to the diffusion of ions and can provide higher specific capacity. However, The effect of the concentration of reactants on microstructure and electrochemical performance of δ-MnO₂, which has been less studied. Herein, the δ-MnO₂ deposited on carbon fabric as the cathodes of AZIBs by four different reactant concentrations (0.05 M, 0.07 M, 0.10 M, and 0.12 M) of potassium permanganate solution were successfully prepared. The electrochemical properties of AZIBs fabricated by reactant concentrations of 0.10 M KMnO₄ were excellent. The δ-MnO₂/CC-0.10 M cathode provided higher rechargeable capacity of 268 mA h•g⁻¹ at 0.1 A•g⁻¹, outstanding rate capability, and long cycle life of 97.3% preservation after 500 cycles at 2A•g⁻¹. This study systematically demonstrates the influence of reagent concentration on the efficiency and stability of aqueous zinc–manganese ion batteries.