Carbon nanodots (CNDs) are photoluminescent, carbon-based nanomaterials with unique features like high fluorescence, water solubility, surface tunability, and low toxicity. These properties have positioned them as multifunctional tools in biomedicine, food safety, environmental monitoring, and sustainable agriculture. In the biomedical field, CNDs support bioimaging, targeted drug delivery, and cancer therapy via photothermal and photodynamic approaches. In food safety, they function as sensitive sensors for detecting heavy metals, pesticides, and microbial contaminants, and are also used in smart packaging. Environmentally, CNDs help monitor pollutants in soil and water due to their chemical responsiveness. In agriculture, they enhance seed germination, nutrient uptake, stress tolerance, and crop yield, while supporting early disease detection, nanofertilization, and pest control. Despite these advancements, challenges such as inconsistent synthesis, potential nanotoxicity, environmental persistence, and regulatory gaps must be addressed. Issues like unpredictable fluorescence in complex food matrices and impacts on soil microbiota raise concerns. Continued research is focused on refining CND synthesis, improving biocompatibility, and integrating CNDs with precision technologies. This chapter underscores their broad applicability while stressing the importance of risk assessment and standardized methodologies to ensure their safe and scalable use in scientific and industrial settings.