A Cu–Pt nanoparticle catalyst supported on TiO₂ nanowires (NWs) was prepared through regenerative counterion exchange–reduction using polyelectrolyte brush as template. Cationic polydimethyl aminoethyl methacrylate brushes were grafted onto TiO₂ NWs. Cu–Pt nanocrystals were produced by anionic counterions CuCl₄²⁻ and PtCl₆²⁻ bound with the polymer brush through in situ reduction with NaBH₄ of high density and low polydispersity. The as-prepared TiO₂ NWs/polymer brush/Cu–Pt was characterized by Fourier transform infrared spectroscopy (FT-IR spectrometry), X-ray photoelectron spectroscopy, transmission electron microscopy, and UV–Vis adsorption spectrometry analyses. Results showed that the highly dispersed Cu and Pt nanoparticles were present on the surface of the TiO₂ NWs/polymer brush. The resultant TiO₂ NWs/polymer brush/Cu–Pt exhibited extremely high catalytic activity and reduced p-nitrophenol at room temperature.