Over the decades, metal and metal oxide nanoparticles (M-MO NPs) have attracted remarkable interest because of their significance in catalytic, magnetic and optical applications in a variety of fields. Despite the existing several physical and chemical synthetic routes, there is still a demand for better and eco-friendly approaches for the preparation of M-MO NPs. In this regard, we have successfully developed a rapid, non-toxic, and green protocol for the synthesis of M-MO NPs using plant extracts. As observed in many organic transformations, bimetallic transition metal based nanoparticles have shown higher catalytic activity than their monometallic counterparts. In this regard, we have synthesized bimetallic, trimetallic, and bimetallic oxide nanoparticles by green approach for catalytic activity. Herein, we present a facile and green approach for the synthesis of M-MO NPs using plant extract as reducing and capping agent. The synthesized M-MO NPs were applied as nanocatalysts for the organic transformations (Scheme 1). Moreover, the well characterized nanoparticles can be retrieved and reused for consecutive reactions without any significant loss in catalytic activity.