<p>Carbon quantum dots (CQDs), a novel class of zero-dimensional carbon-based nanomaterials, have attracted widespread interest due to their remarkable optical, electronic, and chemical properties, such as tunable photoluminescence, excellent biocompatibility, high surface area, and environmental friendliness. In this study, we report a facile, efficient, and scalable synthesis route for CQDs via a one-pot hot injection technique. This method involves the controlled thermal decomposition of an organic carbon precursor in the presence of a high-boiling point solvent and a surface passivation agent, enabling the formation of well-dispersed, highly luminescent CQDs with uniform particle size distribution. The synthesized CQDs exhibit strong and stable photoluminescence emission, which can be attributed to their quantum confinement effect and abundant surface functional groups introduced during synthesis. To explore their potential in environmental applications, the photocatalytic activity of the CQDs was evaluated by monitoring the degradation of Indigo Carmine (IC), a commonly used but environmentally persistent dye, under ultraviolet (UV) irradiation. The CQDs demonstrated outstanding photocatalytic performance, achieving significant degradation efficiency within a short irradiation period. The enhanced photocatalytic behavior is attributed to their efficient light-harvesting capability, rapid charge separation, and generation of reactive oxygen species. Radical scavenging studies were also carried out to understand the mechanism behind photocatalytic degradation of IC dye using carbon dots. This study not only introduces a straightforward and reproducible method for synthesizing high-performance CQDs but also highlights their effectiveness as a standalone photocatalyst for dye degradation. The findings pave the way for the development of sustainable nanomaterials for advanced environmental remediation technologies.</p>