We report a facile and efficient strategy for preparing flower-like hierarchical mesoporous carbon superstructures (FMCS) through a one-pot hydrothermal reaction of nickel acetate with glucose. In the fabrication process of FMCS, the nickel acetate ingeniously plays multifunctional roles: as inducer of flower-like hierarchical carbon, as catalyst of graphitization, and as pore-forming agent. First, flower-like Ni(OH)2/polysaccharide microspheres were self-assembled via a hydrothermal reaction at 180 °C for 24 h. Second, flower-like mesoporous carbon superstructures were obtained by etching and removing the Ni from the Ni/C precursor carbonized from the Ni(OH)2/polysaccharide microspheres. The obtained flower-like superstructures are composed of two-dimensional mesoporous carbon petal building blocks, with a thickness of 20 nm. Electrochemical data showed that the product FMCS-1 displayed a specific capacitance of 226 F g−1 at 0.5 A g−1, and retained 82% (185 F g−1) at a high current density of 20 A g−1, indicative of outstanding rate capability. Furthermore, the three-dimensional (3D) flower-like hierarchical mesoporous carbon superstructures demonstrated excellent cycling stability, with approximately 100% retention of the initial specific capacitance after 2000 cycles at a current density of 10 A g−1.