In the work, we have successfully fabricated an aqueous, high potential asymmetric supercapacitor (ASC) based on Co3O4/reduced graphene oxide nanoribbon (RGONR) hybrid electrodes. Here, Co3O4/RGONR film worked as the positive electrode while RGONR film served as negative electrode in the designed ASC. Uniformly immobilized Co3O4 nanoparticles (NPs) onto graphene nanoribbon have the advantage of high electronic conductivity via underlying RGONR with short ion diffusion path in uniform mesoporous structure. As a consequence, ASC Co3O4/RGONR//RGONR exhibited 1.6V wide operating potential window for charge storage along with significantly improved capacitive performance than symmetric counterpart. It also demonstrates superior device performance with energy density, 64.2Whkg−1 (much higher than that of symmetric cell) with high power density, 8.3kWKg−1 due to optimized mass ratio of the electrodes. In addition, it reveals long term charge/discharge cycling stability with ~94% capacitance retention after 2000 cycles. This high-performance hybrid ASC pave their way for promising applications of pulse power systems.