Carbon quantum dots (CQDs) are a special type of nanostructure characterized for their low toxicity, environmentally friendliness, and ease of manufacture from varied carbon sources like carbohydrates. This carbon source is abundant in natural products and organic wastes, and it is suitable to be used in food applications like nano sensors for food quality and safety. Indeed, CQDs are foreseen as a potential new type of practical and unexpensive sensor to detect harmful substances commonly found in food. Limits of detection (LOD) of CQDs nano sensors have reached concentration level standards established by European Food Safety Authority for additives and heavy metals; nevertheless, for pathogens, safe limits of LOD are still not achieved. This study aims to carry out a review of CQDs obtained from carbohydrates of natural products and organic wastes as well as to describe their performance as sensors of additives, pathogens, and heavy metals in food quality and safety.