Composition design and morphology control can lead to high performance electrode materials for energy storage devices. In this work a graphene/porous Fe2O3 nanocomposite anode material is fabricated via a template-assisted nanocasting process. This nanocomposite consists of graphene scaffold with high electronic conductivity and interconnected Fe2O3 with porous structure, thus exposing ample active sites for redox reactions and offering sufficient contacts with the electrolyte. Owing to these morphological advantages, the nanocomposite outperforms nearly all the reported Fe-based anode materials by delivering a high specific capacitance of 1095Fg−1 at a current density of 3Ag−1. In addition, the material shows great rate capability and good cycling stability. Asymmetric supercapacitors are fabricated by assembling the graphene/porous Fe2O3 nanocomposite (as the anode material) with a CoNi-layered double hydroxide/carbon nanotube composite (as the cathode material). The devices exhibit high energy and power densities of 98.0Whkg−1 and 22,826Wkg−1, which are among the best performances reported to date for asymmetric supercapacitors.