Prussian Blue nanoparticles were grown on the graphene oxide sheet through a one-pot in situ synthesis. The microscopic studies revealed that the PB nanoparticles formed are distributed uniformly on the graphene sheet. A symmetric supercapacitor in the interdigitated form was fabricated using a polyvinyl alcohol-based gel electrolyte. The intercalation/deintercalation of alkali metal ions into the crystalline structure of PB causes the oxidation of the metal center. The high surface area (99.931 m2/g) enhances the electrochemical response of the composite. The fabricated supercapacitor showed an areal capacitance of 68.86 mF cm−2 with 0.0215 mWh cm−2 areal energy density and 4.125 mW cm−2 areal power density. The device could retain 95.3 % of the areal capacitance after 2000 cycles.