Carbon Quantum Dots (CQDs) are versatile nanocarbon materials with high crystallinity, stable photoluminescence, and small in size. Researchers find suitable applications in photocatalysis and electrocatalysis due to their superconductivity, tunable photoluminescence, and quick charge transfer. This review highlights synthetic techniques of CQDs, and characteristics, and showcases ample applications in both photocatalysis and electrocatalysis.