There has been increasing interest in aqueous Zn-ion batteries (ZIBs) because of their absolute safety, but it remains challenging to develop cathode materials with a high rate capability and cycling stability. Herein, we report a one-step strategy to construct a unique two-dimensional (2D) hierarchical structure of Mn₂O₃@graphene. Mn₂O₃ nanosheets are vertically grown on few-layered graphene via a fast one-step molten salts method. Benefiting from the unique 2D hierarchical structure with high electronic and ionic conductivity, as well as the synergetic effect between Mn₂O₃ and graphene, the Mn₂O₃@graphene here displays extraordinary electrochemical performance in ZIBs. In particular, it shows a record high reversible discharge capacity of 850.3 mA h g⁻¹ at a current density of 300 mA g⁻¹. Moreover, a high reversible capacity of 125 mA h g⁻¹ after 5000 cycles at a high current density of 7000 mA g⁻¹ (88.8 mA h g⁻¹ at 30 000 mA g⁻¹) can be achieved. These excellent electrochemical performances of Mn₂O₃@graphene are found to be superior to those of most electrode materials previously reported.