Biosynthesis of silver nanoparticles (AgNPs) by banana leaf extracts was achieved. Plant extracts are not expensive and ecofriendly and thus can be an economic and efficient alternative for the large-scale synthesis of nanoparticles. The AgNPs formed by reaction of banana leaf extracts with aqueous solutions of silver nitrate (AgNO3). The synthesized nano-particles were confirmed by using UV–Vis absorption spectroscopy, X-Ray diffraction (XRD) and Transmission Electron Microscope (TEM). The produced AgNPs has been applied on cotton fabric to impart antimicrobial efficacy by exhaustion method. The treated cotton fabric shows a clear microbial resistance against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. The treatments of produced AgNPs on cotton not only improve its antimicrobial efficiency but also influenced the tensile strength of the fabric sample positively. The treatment was found to enhance the color depth and fastness properties of dyed cotton fabric samples.