Au@Fe3O4@PANI hybrid shells with controllable polyaniline (PANI) coatings as advanced supported catalysts have been fabricated. Specifically, Fe3O4 and Au nanoparticles were assembled on SiO2 templates, followed by conducting polymer PANI coating, leading to the formation of Au@Fe3O4@PANI hybrid shells after the template removal. The resultant supported Au nanocatalysts not only maintain hollow structures but also possess high saturation magnetization (65.46 emu/g). Catalytic tests toward the reduction of 4-nitrophenol in the presence of NaBH4 indicate that PANI and Fe3O4 not only endow high stability and recyclability but also can largely improve the catalytic activity of Au nanoparticles because of their synergetic effects. It is believed that Fe3O4@PANI hybrid shells can be regarded as multifunctional supports for noble metal nanocatalysts with a remarkably improved catalytic performance.