This solar driven water splitting process is highly attractive for alternative energy utilization, while developing efficient, earth-abundant, bifunctional catalysts for both oxygen evolution reaction and hydrogen evolution reaction has remained as a major challenge. Herein we develop an ordered CoMno@CN superlattice structure as an efficient bifunctional water-splitting electrocatalyst, in which uniform Co-Mn oxide (CoMnO) nanoparticle are coated with a thin, continous nitrogen-doped carbon (CN) framework. The CoMnO nano-particles enable optimized OER activity with effective electronic structure configuration and the CN framework serves as an excellent HER catalyst Importantly, the ordered superlattice structure is beneficial for enhanced reactive sited, efficient charge transfer, and structural stability. This bifunctional superlattice catalyst manifests optimized current densities and electrochemical stability in overall water splitting outperforming most of the previously reported single or bifunctional electrocatalysts. Combining with a silicon with a silicon photovoltaic cell, this CoMnO@CN superlattice bifunctional catalyst enables unassited solar water splitting continously for similar to 5 days with a solar-to-hydrogen conversion efficiency of similar to 80%. Our discovery suggests that these transition metal oxide-based superlattices may serve as a unique structure modality for efficient bifunctional water splitting electrocatalysts with scale-up potentials.