In an aqueous mixture of manganese acetate, ammonium acetate and pyrrole, PPy and MnO2 composite materials (PPy‐MnO2) are synthesized by i‐t technology at 0.9 V vs. SCE. The influences of manganese acetate to pyrrole in the electro‐codeposition solution on morphologies and charge storage properties of the composite are discussed. PPy‐MnO2 composite materials as the electrode material exhibit a wide charge‐storage potential window of 1.2 V (between −0.3 and 0.9 V vs. SCE) and a high specific capacitance of 345.54 F g−1 at 2 mA cm−2. A symmetric flexible supercapacitor (PPy‐MnO2//PPy‐MnO2) is assembled by using PPy‐MnO2 composite electrodes. PPy‐MnO2//PPy‐MnO2 model supercapacitor displays almost 100% capacitance retention on the different bending angles. The energy density of 37.63 Wh kg−1 at the power density of 830 W kg−1 and an immense cyclic charge‐discharge stability, the specific capacitance is lost less than 3% after the 10,000 galvanostatic charge‐discharge cycles. The successful synthesis of high performance composite electrodes using electro‐codeposition method could open up new opportunities for high energy density supercapacitors. The PPy‐MnO2 electrode has a large charge storage potential window 1.2 V (between −0.3 and 0.9 V vs. SCE). Three‐dimensional nanosheets of PPy were directed through electro‐codeposition with MnO2. In the assembled supercapacitor, although the same PPy‐MnO2 composite films were used as the electrode materials for both of the anode and cathode, charges were stored through different electrochemical process in anode and cathode. The supercapacitor also demonstrated a good cyclic charge‐discharge stability, > 97% of the specific capacitance can be maintained after 10000 cycles. [ABSTRACT FROM AUTHOR]