Mitochondrial dysfunction is considered one of the key drivers of neurodegeneration and pathological aging, characterized by impaired energy production, oxidative stress, disrupted mitophagy, and biogenesis. Because mitochondria regulate bioenergetics, redox balance, and neuronal survival, therapeutic strategies that restore mitochondrial integrity are of growing interest. This review outlines mechanisms of mitochondrial function and failure, links them to Alzheimer's and Parkinson's disease, and summarizes evidence on phytochemicals and mitochondria-targeted small molecules, which enhance biogenesis, mitophagy, respiratory efficiency, and antioxidant defence in preclinical models together with life-style interventions. Although many compounds demonstrate preventive rather than restorative benefit and clinical evidence remains limited, next-generation approaches, including nanoparticles for mitochondrial delivery, mtDNA editing, and mitochondrial transfer, suggest increasing therapeutic potential. We underline that future success will rely on improved delivery, synergistic combinations, and rigorous clinical trials. Mitochondria-directed therapies may ultimately provide disease-modifying or preventive strategies for neurodegenerative disorders.