Flower-like MnO2 decorated activated multihole carbon (AMC) was fabricated by a simple but effective strategy. Such unique MnO2@AMC nanocomposite exhibited the optimized pseudocapacitance performance, revealing a specific capacitance (297.8 F g−1) with excellent rate ability. An asymmetric supercapacitor with nanocomposite as the positive electrode and activated graphene (AG) as the negative electrode yielded an energy density of 18.04 W h kg−1 and a maximum power density of 8.97 kW kg−1. And thus, this facile synthetic strategy could be useful to design high-performance electrode for supercapacitors.