Innovative methods to develop a metal ion sensor to detect heavy metal ions have played a pivotal role in protecting the environment from pollution. This study aims for a detailed review of metal sensing and the development of a metal sensor based on the chemical carbonization technique, producing Chemical Carbon Dots (CCDs) using less hazardous chemicals such as urea and charcoal for Hg (II) metal ion sensing. The uniqueness and advantage of this study is the development of CCDs with high quantum yield (57%), pink fluorescent, highly stable, and N-doped CCDs from chemical carbonization using nitrogen source. The spectrochemical studies using UV − vis, photoluminescence spectroscopy, Fourier transform infrared, and X-ray photoelectron spectroscopy analysis revealed the presence of hydroxyl-, carbonyl-, and nitrogen-containing groups and also found that carbon, oxygen, and nitrogen are present in very high amounts. Morphological analysis confirmed that the synthesized CCDs were spherical in shape with an average size of 2 nm. The studies imply that the prepared CCDs are highly selective toward the sensing of Hg (II) ion, a deadly toxic heavy metal ion contaminant. The developed novel Hg (II) ion sensor showed a large blue shift in wavelength from 538 to 473 nm with the lowest quenching.