Peptides have been regarded as useful biomolecule templates to control the synthesis of various inorganic nanomaterials in mild conditions. Inspired by this, the easily self-assembled amyloid β (Aβ) peptide was developed as an alternative template to prepare Au nanostructures for the enhanced catalytic activity, for instance, the reduction of 4-nitrophenol. The presence of Aβ peptide assemblies with different structures could direct the nucleation of Au to form different Au nanostructures. Using the Aβ25-35 monomers, nanoribbons, and nanofibrils prepared by the self-assembly in phosphate buffered (PB) solution at 0, 3, and 12 h, respectively, as templates could controllably prepare Au nanospheres, nanoribbons, and nanofibers, while the Aβ25-35 monomers prepared by the self-assembly in water at 0 h could direct the synthesis of Au nanoflowers. The Aβ25-35-templated Au nanostructures had different catalytic activities due to the size and structure effects, which however are significantly enhanced as compared with the template-free Au nanoparticles.