Silver nanoparticles supported on superparamagnetic iron oxide (SPION)-Tween20 nanocomposite were prepared by a combined polyol and chemical reduction routes. The morphology, composition and structure of Fe3O4@Tween20@Ag nanocatalyst were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy, energy dispersive X-ray spectroscopy, thermal gravimetric analyzer, and X-ray powder diffraction. In addition the magnetic properties were evaluated with vibrating sample magnetometry. It was found that Fe3O4@Tween20@Ag nanocatalyst could catalyze the degradation of various organic azo dyes and could easily be recovered from the reaction medium with external magnet. Also, the magnetic catalyst can be succesfully recycled and reused for at least five successive degradation cycles of methyl orange, methylene blue and Rhodamine B, confirming a high recycling efficiency. The cost effective and recyclable Fe3O4@Tween20@Ag nanocatalyst provide an novel nanomaterials architecture for environmental remediation applications.