A novel nanocomposite of Co₃S₄ hollow nanospheres grown on reduced graphene oxide (rGO) has been synthesized by a facile two-step method and used as an advanced electrode material for supercapacitors. The intriguing formation and attachment mechanism of these Co₃S₄ hollow nanospheres on graphene are investigated. More importantly, it is found that the electrochemical performance of the as-prepared nanocomposite could be effectively improved by the chemical interaction between rGO and Co₃S₄. Specifically, it exhibits a high specific discharge capacitance of 675.9 F g⁻¹ at 0.5 A g⁻¹ and 521.7 F g⁻¹ at 5 A g⁻¹. These results suggest the great promise of fabricating graphene-supported hybrid materials for high-performance energy applications.