We herein investigated the growth behavior and dual-plasmon enhanced dual-functional catalytic activity of Au/Cu_2−xS hybrids. The growth of plasmonic Cu_2−xS on Au nanocrystals was achieved through an aqueous solution method. By monitoring the morphological transition, the Cu_2−xS shells were found to start growing at a random position on the surface of the Au nanospheres or nanorods, and then continued to expand or further grew at a new position to form half-shell or anisotropic Au/Cu_2−xS hybrids, thereby completely wrapping the Au cores. The variation trend of strong plasmon coupling between Au and Cu_2−xS was clarified, which endows Au/Cu_2−xS hybrids with intense absorption in the UV-vis-NIR region. Subsequently, the excellent dual-plasmon enhanced dual-functional catalytic activity of half-shell Au(nanospheres)/Cu_2−xS hybrids was demonstrated by evaluating the degradation rate of methylene blue in the presence of H₂O₂ under light irradiation (λ > 420 nm). We found that the heterogeneous Fenton-like reaction (both Au and Cu_2−xS are Fenton-like reactants) and photocatalytic process simultaneously occur on the half-shell Au/Cu_2−xS hybrids. Meanwhile, these two types of degradation processes can be remarkably accelerated by the strong dual-plasmon coupling of Au and Cu_2−xS.