In recent years, resistance to commercially available antimicrobial agents by pathogenic bacteria has become a serious problem. Hence, there is a need for environmentally safe drug to use as antimicrobial agent. Nanotechnology is the fast-growing science with commercial applications in many sectors, including therapeutics. This study aims to evaluate vitamin B1 encapsulated chitosan nanoparticle (VCNP) for its antibacterial activity. Antibacterial activity of the VCNP was performed by disk diffusion method against two strains of gram-positive bacteria (Bacillus subtilis, Staphylococcus aureus) and three strains of gram-negative bacteria (Escherichia coli, Salmonella typhimurium, and Klebsiella pneumonia). VCNP exhibited the highest antimicrobials activity against E. coli (20 ± 0.63mm), followed by K. pneumonia (18 ± 0.42mm), S. typhimurium (14.6 ± 0.75mm), B. subtilis (14.3 ± 0.55mm), S. aureus (13 ± 0.48mm). The present study suggest that VCNPs can be used as potential antibiotic drug.