MnO2 was deposited on Ni nanocone arrays through electrochemical deposition process, to enhance the electrochemical performance. The as-prepared MnO2/Ni nanocone electrode can be peeled off from the substrate and used as freestanding, flexible, and ultrathin supercapacitor electrode. Its specific capacitance is as high as 325 F/g. The electrode also shows excellent rate performance. The flexible and ultrathin asymmetric supercapacitor based on the MnO2/ Ni nanocone elelctrode demostrates good electrochemical performance. The device possesses promising applications in the field of energy storage.