In this study, we prepared lichen reduced-graphene oxide (LrGO)-bimetallic nanoparticle nanocomposites (LrGO-AgAu) by applying a green, facile and one pot approach. LrGO-AgAu was synthesized via simultaneous reduction of graphene oxide (GO), AgNO3 and HAuCl4 with Cetraria Islandica (L.) Ach. extract. Characterization of the prepared nanocomposites were carried out by transmission electron microscopy (TEM), scanning electron microscopy (SEM), ultraviolet-visible (UV-Vis) spectroscopy, X-Ray Diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA). The synthesized LrGO-AgAu bimetallic nanoparticle nanocomposites were used for catalytic conversion of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) with NaBH4. The effect of nanocomposite composition on catalytic activity was examined. It is obtained that AgAu bimetallic nanoparticles with small particle sizes were decorated LrGO nanosheets homogenously and superior catalytic performance was achieved for the decomposition of 4-NP. The results showed that catalytic reduction reaction of 4-NP to 4-AP with noble metallic NPs nanocatalysts obtained by lichen extract is a facile and low-cost approach for removal.