We have developed a green and environmentally friendly approach for the synthesis of silver nanoparticles (Ag NPs) using Radix Puerariae plant extract via a novel chemical route. The prepared Ag NPs has been characterized by TEM, XRD, SEM, DLS, EDX, and UV–Vis. Further, catalytic application of this fascinating nanomaterial has been utilized in the synthesis of biologically important pyrimido[1,2-b]indazole derivatives via one-pot three-component coupling reaction between aldehydes, alkynes and amines with excellent yields under solvent-free conditions. After completion of the catalytic reaction, the Ag NPs could be easily recovered and reused for four times without significant loss in its catalytic activity.