Neurodegenerative conditions like Alzheimer’s and Parkinson’s lead to nerve cell decline and impaired brain function over time. Current medications manage symptoms but do not effectively halt or reverse these diseases. Recently, interest has grown in using plants and their compounds to protect the brain, potentially with fewer side effects. Many plants contain healing substances that may safeguard brain health by enhancing the body’s defense mechanisms against disease and injury. Key compounds include flavonoids (quercetin, rutin), alkaloids (berberine, huperzine A), terpenoids (ginkgolides, bilobalide), and polyphenols (curcumin, resveratrol). These substances combat harmful particles and activate the Nrf2/ARE pathway, boosting internal antioxidants. They also help control brain inflammation, regulate chemicals like acetylcholine and dopamine, balance calcium, and support cellular energy production. Additionally, phytochemicals promote brain flexibility by activating the BDNF/TrkB pathway, preventing protein clumping, and managing cell death. Emerging research indicates they may also protect the blood–brain barrier and improve cerebral blood flow. Understanding these mechanisms is crucial for developing natural therapies for neurodegenerative diseases, strokes, and brain injuries, ultimately advancing phytochemical-based drug development and improving outcomes in neurological disorders.