A novel and green approach based on the biosynthesis of palladium nanoparticles on modified graphene oxide by Origanum vulgare leaf plant extract have been developed by our group. The prepared magnetically nanocatalyst was characterized by transmission electron microscopy, scanning electron microscopy, X-ray diffraction, vibrating sample magnetometer (VSM) and Fourier transform infrared spectroscopy. The heterogeneous catalytic system was investigated for the reduction of 4-nitrophenol, methylene blue and methyl orange in the presence of NaBH4 as a reducing reagent and also for Suzuki–Miyaura cross-coupling reactions between phenylboronic acid and a range of aryl halides (X = I, Br, Cl). Moreover, synthesized catalyst could be readily recycled and reused several times without significant loss of activity