Since their discovery in 2004, carbon quantum dots (CQDs) have attracted significant attention due to their unique properties, including excellent hydrophilicity, biocompatibility, high electrical conductivity, low toxicity, and tunable fluorescence. These characteristics make them highly promising for detecting and removing hazardous contaminants. This chapter explores the innovative applications of CQDs in environmental sensing and pollutant removal. It presents a reader-friendly overview of the various synthesis methods for CQDs, ranging from top-down to bottom-up approaches, emphasizing sustainable and cost-effective strategies. The discussion then focuses on their use as electrochemical sensors for detecting toxic compounds and their role in the adsorption of organic and inorganic pollutants from water. Finally, the chapter addresses the current challenges and perspectives regarding the environmental applications of CQDs and highlights future directions for advancing their use in environmental remediation.