Cancer is a global concern and a major cause of early deaths as well as poor lifestyles. One of the prime research areas of cancer includes nanotechnology and its applications. Many nanomaterials like carbon nanotubes, nanoshells, nanorod arrays, polymer dots, quantum dots, etc have been highlighted owing to their excellent characteristics aiding in cancer diagnostics and therapeutics. In this paper, the authors aim to highlight the application of one of such nanostructures, i.e, Carbon quantum dots (CQDs). These nanoparticles have seen widespread application in cancer due to their special optical characteristics, high quantum yield as well as good electrical properties. They also possess excellent photostability. The past few decades have seen their application in diagnostic devices, assays, biosensors, bioimaging, drug delivery, and other therapeutic applications as well. The review summarizes its remarkable characteristics and recent trends in cancer diagnostics and therapeutics. The outcome of our literature review highlights that CQDs are able to detect specific types of cancer and differentiate between normal and malignant cells, hence, making cancer diagnosis more efficient. Similarly, in cancer therapy, the excellent photoluminescence property of CQDs has been well exploited in drug delivery.