Aim: The present study aimed to prepare chitosan nanoparticles, characterize it, and study the setting reaction of conventional GIC using Fourrier Transform Infra-red spectroscopy after adding 10% chitosan nanoparticles to the powder to enhance its antibacterial activity. The antibacterial effect against Streptococcus mutans and fluoride ion release were investigated. Methodology: Nanoparticles of chitosan were produced by ionic gelation method and their size was determined by TEM. FTIR analysis was done for conventional GIC and nanochitosan-modified GIC groups. Direct contact test determined antibacterial activity while an ion-selective electrode and analyzer measured fluoride ion release in ppm where n=9 for each test. Results: TEM revealed that the size of chitosan nanoparticles was 19-47 nm. FTIR spectrographs revealed that nanochitosan did not interfere with the setting reaction of conventional GIC and interaction occurred between NH2 in chitosan with carboxyl and hydroxyl functional groups of conventional glass ionomer cement. Nanochitosanmodified GIC showed higher antibacterial activity and significantly higher mean values of fluoride ion release compared to the conventional GIC group. Conclusion: Adding 10% w/w of chitosan nanoparticles to conventional GIC enhanced its antibacterial activity against Streptococcus mutans and fluoride ion release. Therefore, it can be considered as a promising additive to GIC to promote its anticariogenicity.