Abstract Functionalized carbon quantum dots (CQDs) show great potential for application in the field of food safety. CQDs have attracted widespread attention in this regard due to the wide range of sources of raw materials for their synthesis, and their good biocompatibility and stable fluorescence. This paper analyses the properties of CQDs and compares with those of conventional semiconductor quantum dots (SCQDs). It analyses the similarities and differences between hydrothermal carbonization, pyrolysis and microwave-assisted synthesis of CQDs, and reviews the principles and methods of functionalization of CQDs through surface modification and doping. Finally, it discusses the applications of functionalized CQDs in food safety, such as detection and sensing, bio-inhibition and photocatalytic degradation, and the mechanisms of detection.