The development of simple and cost-effective chemosensors for detecting heavy metal ions is of significant environmental importance. Herein, this article describes Citric acid isolated from lime juice as optical chemosensor for Cd² ions using UV–Visible spectroscopy. The isolated citric acid was characterized using UV-Visible, ¹H-NMR and FT-IR spectroscopy.  The absorption spectrum exhibited a characteristic peak around 285–295 nm corresponding to n → π* transitions of carbonyl groups. Upon addition of Cd² ions, change in absorbance intensity was observed, indicating complex formation. The results showed that absorption intensity was concentration-dependent, that is when the concentration of Cd²⁺ increased from (0.01–0.08 ppm), the intensity Increased. This trend indicates that the citric acid-based system responds proportionally to changes in cadmium concentration. The results demonstrate that citric acid can serve as a low-cost and eco-friendly optical probe for cadmium detection.