Supercapacitor performance is reported for manganese silicate hybridized carbon materials (MnSi-C) that is derived from natural bamboo leaves. The in-situ generated manganese silicate is in good distribution by a simple hydrothermal treatment without the addition of another controlling agent. We also study the performance of MnSi-C as a single electrode and a cathode for fabrication of asymmetric supercapacitor device with a Ni(OH)2 anode. Remarkably, the single electrode MnSi-C-3 delivered a capacity of 162.2 F g-1 at a current density of 0.5 A g-1. The cyclic performance of single electrode MnSi-C-3 maintains high capacitance retention of 85% after 10,000 cycles of charge-discharge. By assembled MnSi-C-3 with Ni(OH)2, the asymmetric supercapacitor device shows a capacity of 438.5 mF cm-2 at a scan rate of 4 mA cm-2. The device exhibits an optimal electrochemical performance with an energy density of 3 mWh cm-3 (24.6 Wh kg-1) and power density of 130.4 mW cm-3 (604.8 W kg-1). A reasonable mechanism of in-situ generated manganese silicate on the surface of carbon is proposed based on the experimental data and existed theories. This MnSi-C nanocomposite proves to be a promising electrode material for high energy supercapacitor.