Dementia is a neurodegenerative disorder that causes gradual deterioration in cognitive functions. It affects majority of people worldwide. There are few and limited available treatments for this disorder. Various novel discoveries have been made in the area of plant-based nanomaterials, and this demonstrates a promising future for great therapeutic approach as a result of diverse phytochemicals which includes alkaloids, tannins, flavonoids, saponins, and many others, which are important for nanomaterial synthesis and play important roles in contemporary treatment approaches for various disorders, including dementia. Plant-based nanomaterials demonstrate an effective and efficient strategy for treating dementia due to their biocompatibility, blood brain barrier penetrating ability, and low toxicity. This chapter highlights the usage of plant-based nanomaterials in the treatment and management of dementia, exploring their antioxidant, neuroprotective, and anti-inflammatory actions. The mechanisms of action of these nanomaterials on dementia pathogenesis, such as hyperphosphorylation of tau, oxidative stress, amyloid-beta aggregation, and neuroinflammation, are discussed. Moreover, the abilities of plant-based nanomaterials to increase efficacy treatment, decrease adverse effects, and improve drug delivery are investigated. In conclusion, the use of plant-based nanomaterial is a novel approach that has the potential to improve patient outcomes and make a way for future therapeutic applications in dementia’s treatment.