The utilization of biological‐waste materials to synthesize heteroatom‐doped activated carbon (AC), followed by metal oxide functionalization for high‐performance supercapacitors is described. Herein, easily available and cheap biowaste, i.e., cow dung (CD), and low priced‐nontoxic waste melamine sponge (MS) are consumed to produce nitrogen‐doped AC followed by functionalization with economically inexpensive manganese dioxide (MnO2), that is utilized to provide an efficient energy‐storage material. The use of CD, MS, and MnO2 materials furnishes the process with sustainability, cost‐effectiveness, and safe components for the doping of heteroatoms and metal oxide on the carbon framework for energy‐storage applications. The subsequent material exhibits maximum specific capacitance, i.e., 424 F g−1, at a current density of 1 A g−1, which relates to maximum power as well as the energy density of 1817 W kg−1 and 47.7 Wh kg−1, respectively. The resultant material shows high‐performance specific capacitance and excellent cyclic stability for supercapacitor applications. This modest process of the direct production of N‐doped AC followed by MnO2 functionalization is a simple, economical, large production of a nanomaterial prototype for different applications including supercapacitor applications.