Flavonoids are a large and diverse group of natural compounds found in plants—over 10,000 have been identified so far. Plants produce these substances as secondary metabolites to help regulate growth and defend against stress. In humans, flavonoids are linked to a wide range of health benefits. A body of evidence highlights how regular consumption of flavonoid-rich foods—like fruits, vegetables, tea, and dark chocolate—contribute to a low risk of developing chronic diseases, including several types of cancer. What makes flavonoids especially interesting in cancer research is their ability to influence key cellular pathways that often go awry in cancer cells—such as PI3K/Akt, MAPK, and NF-κB. These pathways control essential processes, such as cell proliferation, apoptosis, angiogenesis, and metastasis. While conventional drugs targeting these pathways can be effective, they often present with serious side effects, drug resistance, or unintended activation of compensatory pathways. Flavonoids, by contrast, offer a safer, multi-pronged approach: they can block pro-survival signals that support cancer cells while simultaneously turning on pro-apoptotic signals that trigger their death. This dual action helps curb tumor growth, limit their angiogenesis, and boost cancer cells’ responsiveness to standard treatments. Despite their promise, flavonoids face practical challenges. They have low bioavailability, rapid metabolism, and variable efficacy across tumor types. To transition from promising experimental agents to clinically viable therapeutic options, researchers need to develop smarter delivery methods (like nanoparticles or liposomes), improve the stability of the compounds, and explore their combination with existing drugs through a rigorous clinical trial.