This review focuses on the potential of carbon dots (C-dots) as antimicrobial, antiviral, and anticancer agents. C-dots, discovered in 2004, are a type of carbon-based nanomaterial with unique properties such as low toxicity, ease of synthesis, high dispersibility, and biocompatibility. The review is divided into four sections: structure, surface functionalization, morphology, and classification of C-dots; synthesis methods; biological activities; and biocompatibility and toxicity. **Structure and Surface Functionalization:** C-dots are typically less than 10 nm in size and have a core-shell structure with a carbogenic core and a polymer shell. They can be negatively or positively charged depending on the functional groups present, which affects their antibacterial and antiviral activities. The surface functional groups, such as -OH, -COOH, -CHO, -NH2, and -SH, play a crucial role in their biological properties. **Morphology and Size:** C-dots can have various morphologies, including disk-shaped and quasi-spherical structures. Their size and shape influence their antibacterial and antiviral activities. Smaller C-dots are more effective due to their ability to penetrate cell membranes and produce reactive oxygen species (ROS). **Classification:** C-dots are classified into four main types: graphene quantum dots (GQ-dots), carbon quantum dots (CQ-dots), carbon nanodots (CN-dots), and carbonized polymer dots (CP-dots). Each type has unique properties that make them suitable for different applications. **Synthesis Methods:** C-dots can be synthesized using both top-down and bottom-up approaches. Top-down methods involve breaking down larger carbon structures into smaller ones, while bottom-up methods involve assembling smaller carbon structures into C-dots. Common synthesis methods include arc discharge, laser ablation, electrochemical oxidation, and hydrothermal processing. **Biological Activities:** - **Antimicrobial Activity:** C-dots exhibit potent antimicrobial activity against bacteria, fungi, and viruses. They work by producing ROS, disrupting cell membranes, and damaging DNA/RNA. - **Antiviral Activity:** C-dots can prevent viral infections by blocking attachment, penetration, replication, and budding. They have shown effectiveness against various viruses, including coronaviruses and flaviviruses. - **Anticancer Activity:** C-dots are promising for cancer treatment due to their ability to deliver drugs directly to tumor sites. They can enhance the efficacy of drugs like doxorubicin (DOX) and improve drug targeting. **Biocompatibility and Toxicity:** C-dots are generally biocompatible, with minimal effects on blood components and no significant impact on blood coagulation. However, their long-term effects and potential toxicity need further investigation. Overall, C-dots show great potential as versatile nanomaterials for biomedical applications,This review focuses on the potential of carbon dots (C-dots) as antimicrobial, antiviral, and anticancer agents. C-dots, discovered in 2004, are a type of carbon-based nanomaterial with unique properties such as low toxicity, ease of synthesis, high dispersibility, and biocompatibility. The review is divided into four sections: structure, surface functionalization, morphology, and classification of C-dots; synthesis methods; biological activities; and biocompatibility and toxicity. **Structure and Surface Functionalization:** C-dots are typically less than 10 nm in size and have a core-shell structure with a carbogenic core and a polymer shell. They can be negatively or positively charged depending on the functional groups present, which affects their antibacterial and antiviral activities. The surface functional groups, such as -OH, -COOH, -CHO, -NH2, and -SH, play a crucial role in their biological properties. **Morphology and Size:** C-dots can have various morphologies, including disk-shaped and quasi-spherical structures. Their size and shape influence their antibacterial and antiviral activities. Smaller C-dots are more effective due to their ability to penetrate cell membranes and produce reactive oxygen species (ROS). **Classification:** C-dots are classified into four main types: graphene quantum dots (GQ-dots), carbon quantum dots (CQ-dots), carbon nanodots (CN-dots), and carbonized polymer dots (CP-dots). Each type has unique properties that make them suitable for different applications. **Synthesis Methods:** C-dots can be synthesized using both top-down and bottom-up approaches. Top-down methods involve breaking down larger carbon structures into smaller ones, while bottom-up methods involve assembling smaller carbon structures into C-dots. Common synthesis methods include arc discharge, laser ablation, electrochemical oxidation, and hydrothermal processing. **Biological Activities:** - **Antimicrobial Activity:** C-dots exhibit potent antimicrobial activity against bacteria, fungi, and viruses. They work by producing ROS, disrupting cell membranes, and damaging DNA/RNA. - **Antiviral Activity:** C-dots can prevent viral infections by blocking attachment, penetration, replication, and budding. They have shown effectiveness against various viruses, including coronaviruses and flaviviruses. - **Anticancer Activity:** C-dots are promising for cancer treatment due to their ability to deliver drugs directly to tumor sites. They can enhance the efficacy of drugs like doxorubicin (DOX) and improve drug targeting. **Biocompatibility and Toxicity:** C-dots are generally biocompatible, with minimal effects on blood components and no significant impact on blood coagulation. However, their long-term effects and potential toxicity need further investigation. Overall, C-dots show great potential as versatile nanomaterials for biomedical applications,