In this work, we designed a green synthetic route to fabricate carbon quantum dot (CQD) from Annona reticulata leaves and developed it as a water-soluble, stable, and selective fluorescent probe for detecting Cr (III) ions. The generated CQDs exhibit an excitation dependent behaviour in the 280 to 400 nm range with high fluorescence quantum yield (QY) of 12 %. The UV–vis., FT-IR, fluorescence, TEM, and XRD techniques were used to characterize the optical, structural, and morphological properties of the CQDs. Fluorescence quenching of the CQDs in the presence of Cr (III) ions were utilized for the development of the sensor with the aid of PL analysis. We have optimized the reaction conditions such as pH and interaction time to maximize the selective detection ability of the sensor. The linear range and LOD obtained were 0 to 40 μM and 2 μM, respectively. A Stating quenching mechanism is involved in the quenching mechanism. Further, we investigate the ability of CQDs to detect Cr (III) ions in real water sample analysis.