Nickel hydroxide is widely used as cathode materials in metal hydride–Ni (MHNi) and Cd–Ni rechargeable batteries and the asymmetric supercapacitors due to its good electrochemical properties and affordable prices. The specific capacity and cycle life of Ni(OH)2 are greatly declined at high current density due to its P-type semiconductor structure and the mechanism of solid-phase proton diffusion. The paper thus proposes a new controllable complexing–precipitation method to prepare nano-Ni(OH)2 sheets on mesoporous carbon particles, denoted as nano-Ni(OH)2/C composite. Because of the “fusion effect” of the Ni(OH)2 and mesoporous carbon, a sample with 20% carbon can offer 345.2mAhg−1 at ultrahigh current density of 30A g−1 which are higher than that of its theoretical one-electron capacity (291mAhg−1) of Ni(OH)2 during the first 20,000 cycles. Furthermore, the capacity still keeps up to 97% of the initial capacity, which exhibits a superior electrochemical property than the existing Ni(OH)2. The nano-Ni(OH)2/C composite (20% carbon) exhibits a superior electrochemical property than the reported existing Ni(OH)2 and Ni(OH)2/carbon composites in the literature.