The development of composite materials in designed architectures in nanoscale level has been an intriguing research approach for diverse applications. Here, we report synthesis of a ternary nanocomposite of mesoporous cobalt oxide nanohairs, silver nanoparticles and electrospun carbon nanofibers sheet (3D Co3O4-Ag@CNFs) in a novel and apt 3D architecture by cost-effective electrospinning, hydrothermal cum post modification approaches for high performance supercapacitors (SCs). Conditions for controlled growth of constituents and their electrochemical significance have been discussed. The optimized nanocomposite, as a free standing electrode, exhibits a high specific capacitance of 1880 F g(-1) at a current density of 2 Ag-1 which is, possibly, the highest value reported for CNFs based Co3O4 composites. The assembled asymmetric supercapacitor device exhibits a high energy density of 53.8 W h kg(-1) at a high power density of 797.9 W kg(-1) with notable cyclic life. The results recommend the prepared nanocomposite sheet as an efficient electrode for high performance SCs.