Hierarchical Ni-Co-Mn ternary oxide nanosheets on nickel foam have been synthesized by a two-step strategy involving chemical bath deposition (CBD) and subsequent thermal annealing treatment. The Ni-Co-Mn oxide nanosheets are directly used for electrochemical investigation and possess a high specific capacity of 715.1Cg−1 at a current density of 1Ag−1. Furthermore, a hybrid supercapacitor device is successfully fabricated by employing Ni-Co-Mn ternary oxide electrode as positive electrode and activated carbon (AC) as negative electrode. The hybrid supercapacitor device with optimized cell voltage of 1.6V exhibits a maximum energy density of 36.4 Wh kg−1 at a power density of 320Wkg−1 and good cycling stability. The excellent electrochemical behaviors indicate that Ni-Co-Mn oxide nanosheets are highly desirable for high capacity energy storage devices.