Recycling of materials is one way to achieve resource conservation, which could be implemented in new technology to sustain its development. We organize this review to raise awareness of the applications of photoluminescent carbon nanodots (C-dots) to food safety, with an emphasis on C-dots synthesized from food or food wastes. The diverse chemical constituents in agriculture and food products, including wastes, provide a multitude of carbon precursors for C-dots. Some of these C-dots have been developed to function as sensors for food-borne pathogens, heavy metals, and harmful colorants in food products. This process of using food and its byproducts to improve food safety is one step forward in the way of conservation and industry self-efficiency.