The development of bioplastics is currently increasing, because bioplastics are an effort to reduce landfill waste. One of the bioplastics that has good degradation ability is cornstarch. The addition of nanoparticles was carried out to improve the properties of bioplastic packaging. One example of the application of nanotechnology in food packaging is silver nanoparticles (AgNP), known as antimicrobial substances. This research was conducted to determine the effect of adding AgNP (0%, 1%, and 2%) on the antimicrobial and biodegradation of cornstarch bioplastics. Bioplastics are made by casting method. AgNP was used from the synthesis of silver nitrate (AgNO3) and trisodium citrate dihydrate (C6H5Na3O7.2H2O) as a reducing agent and stabilizer by chemical reduction method, which was then analyzed by FTIR. The results obtained showed that cornstarch bioplastic AgNP 1% has the ability to estimate the fastest degradation time among other concentrations with an addition of 103 days. Cornstarch bioplastic AgNP 2% had the best ability to inhibit bacterial growth, with antibacterial inhibition zone diameters of 11.03 mm (Staphylococcus aureus) and 10.61 mm (Escherichia coli). However, AgNP could not inhibit the mold growth of Aspergillus niger. The addition of AgNP to cornstarch bioplastics can increase the degradation capabilities and antibacterial activity of bioplastics. © 2024 Trans Tech Publications Ltd, Switzerland.