Potato peel extract (PPE) is a rich source of polyphenols which could be used as reducing agents for the green synthesis of nanocomposites. The project aims to synthesize Ag/Mg(OH)2 nanocomposites (NCs) by using PPE and investigate its antioxidant activity. The phytochemicals in peel extract act as reducing, stabilizing, and capping agents in the reduction of precursor salts. SEM-EDX analyses of the bio-synthesized Ag/Mg(OH)2 NCs show the formation of Ag nanoparticles (NPs) on the surface of Mg(OH)2 carriers with various sizes in the nanoscale, while XRD patterns suggest the existence of Mg(OH)2 hexagonal crystalline structure. The antioxidant activity of Ag/Mg(OH)2 NCs was assessed through the DPPH free radical scavenging assay with IC50 values between 1.3 and 1.4 mg/mL. Compared to various plant-based Ag NPs, such values are remarkably closer to the IC50 of the standard ascorbic acid (0.6 mg/mL), promoting PPE-based Ag/Mg(OH)2 as an effective and ecofriendly antioxidant.