Antibiotic nanocomposite polymers show great promise in treating a variety of pathogens that cause widespread disease. Sodium alginate-grafted diphenylamine (NaAlg-g-DPA) embedded with different ratios of silver nanoparticles (AgNPs) was fabricated and characterized through different techniques including FTIR, XRD, and SEM techniques for investigating the antimicrobial activity. XRD confirmed the crystallinity of these compounds, and the average crystal size of Na Alg-g-DPA/Ag was estimated to be 48.6 nm. Then it was applied as an antimicrobial agent and evaluated through two ways (inhibition zone and MIC techniques) against Staphylococcus aureus as gram-positive bacteria with an inhibition zone of 19.31.6 mm and 18.60.63 mm against Escherichia coli as gram-negative bacteria while with increasing the Ag ratio 2:1 there was an enhancement in their biological activity to be 21.90.69 mm against Staphylococcus aureus and with an inhibition zone of 21.32.1 mm against Escherichia coli. The outcomes of this investigation are important for the development of new composite materials with antibacterial properties for industrial applications.