Core/shell nanorods of MnO2/carbon embedded with Ag nanoparticles (MCA) were successfully fabricated via a facile and effective hydrothermal and reduction method in situ. Typically, a MCA-1.5 sample (1.5 g.L-1 glucose reactant) exhibited the highest specific capacitance of 628 F.g(-1) at the current density of 1 A.g(-1) in three-electrode systems. Particularly, a fabricated asymmetric supercapacitor, using MCA-1.5 and active carbon as the positive and negative electrodes, respectively, delivered a maximum energy density of 48.3 W.h.kg(-1) at power density of 851.7 W.kg(-1) and exhibited a superior, long cycle life, showing similar to 98.5% specific capacitance retention after 2000 cycles. The practical energy-storage applicability of this device was demonstrated by the operation of an LED bulb when a duo of two such devices was charged. These results indicated that synthesized ternary nanocomposites have potential applications as supercapacitor electrodes in energy storage systems.