Cancer is one of the leading causes of death worldwide. Although there are many different causes for its development, things that can damage the cells such as ultraviolet light and free radicals can be contributors. Protection against cellular damage may be of benefit to the prevention of cancer development and flavonoids, which are natural chemicals found in plants such as fruits and vegetables, have protective properties. This systematic review paper aimed to determine the therapeutic properties of flavonoids in the treatment of cancer. The results showed that all ten studies included in the review were observational studies carried out on human and animal cells. Ten different flavonoids were identified as having a potential role in cancer treatment mainly through promoting cancer cell death; Isolated mimulone-C geranyl flavonoids, baicalein, isoliquiritigenin, wogonin, icariin, fistein, pectolinarigenin, silibinin, sotetsu flavone, and oroxylin A. It was concluded that flavonoids may have a potential therapeutic effect in gall bladder cancer, head and neck squamous cell carcinoma, and oral cancer through it acting on cancer cell death. This study could be used by healthcare professionals to understand that a diet rich in fruits and vegetables may be of benefit to individuals with cancer. However, the results of this study should be interpreted with caution as it was based on animal and human cells and many processes can affect the development of cancer in whole human body systems.