Abstract: As a type of carbon dot (CD) with a positive charge on their surface, cationic carbon dots (CCDs) can be obtained from CDs and amino-containing cationic compounds by one-step or two-step preparation. They not only retain the good fluorescence performance, low toxicity and biocompatibility of CDs, but also improve their gene delivery efficiency and cell uptake capacity. These excellent properties give CCDs potential advantages in the fields of the targeted fluorescence imaging of cancers and gene therapy. This paper reviews the preparation methods and properties of CCDs, suggesting that they can be used as good targeting carriers for imaging cancer and gene therapy. In addition, the basic principles of CCDs for cancer detection and treatment, and their uses in integrated cancer diagnosis and gene therapy are introduced. Current problems and future development trends of CCDs for this purpose are discussed.