Background: Calcium carbonate nanoparticles have been gathering increased attention in the field of biomedicine due to their potential in anticancer treatment and remineralisation abilities. The present study aims to synthesize calcium carbonate nanoparticles using plant extracts of Citrullus lanatus. Methodology: Calcium hydroxide and sodium carbonate solutions were used to produce calcium carbonate solution was reduced to calcium carbonate nanoparticles using Citrullus lanatus extract. The prepared nanoparticles were then characterized using scanning electron microscopy, energy dispersive X-ray analysis and Fourier transform Infrared Spectroscopy Results: The prepared nanoparticles showed amorphous rod shaped morphology in the SEM analysis. FTIR analysis showed the characteristic carbonate peaks at 1480-1410 cm-1 and between 880-860 cm-1 . EDAX analysis showed the presence of calcium, carbon and oxygen content in the prepared nanoparticles. Conclusion: Citrullus lanatus extracts can be used for the synthesis of calcium carbonate nanoparticles, which have a promising avenue in the field of biomedical research. Further studies are necessary in order to develop these nano-particles into a product for clinical use.