A simple green method was developed for the synthesis of silver nanoparticles in the presence of a neomycin-functionalized chitosan as stabilizing agent using a fresh lemon juice as green reducing agent. The stabilizing agent was synthesized based on the Schiff base formation reaction between the chitosan dialdehyde and neomycin antibiotic in 0.05 mM at pH 7.0. The combined form of neomycin antibiotic with chitosan can be used as stabilizing agent for silver nanoparticles (AgNPs) synthesized by a biogenic method using lemon juice as a green reducing agent. The neomycin functionalized chitosan stabilized AgNPs were characterized by various analytical techniques, including UVVisible spectra studies, FTIR, XRD and SEM. The antimicrobial activity of these composite was tested against human pathogenic Gram-positive and Gram-negative bacteria. The synergetic effect of the neomycin functionalized chitosan protected silver nanoparticles was tested against various drug resistant microorganisms. These chitosan derivatives can be used in combination with an anti-bacterial agent to treat and inhibit a resistant bacterial infection or the growth of resistant bacterial infection.