Parkinson’s disease (PD) and Alzheimer’s disease (AD) are a complex neurodegenerative disorders that are both sporadic and familial. It is thought that the abnormal accumulation of α-synuclein and amyloid-β aggregates plays a critical role in the progress of PD and AD, respectively. Therefore, inhibition of α-synuclein amyloid-β aggregation and/or destabilization of α-synuclein and amyloid-β fibrils remain an extremely attractive therapeutic target for the treatment of PD, AD and related neurodegenerative diseases. There is currently no proven therapy to reduce the rate of progression of PD and AD. Strikingly, we discovered Graphene Quantum Dots (GQDs, nanometer-sized carbon nanostructures) with outstanding physical, mechanical and electrical properties, has uniquely broad anti-aggregation properties against neuropathological aggregates such as α-synuclein and amyloid-β. Here we show that theGQDs can bind to α-synuclein and amyloid-β fibrils, and potentially possess the ability of disaggregation and inhibition of α-synuclein and amyloid-β fibrils in vitro and in vivo. Furthermore, our studies strongly show that treatment of GQDs can ameliorate α-synuclein preformed fibrils (PFFs)-induced LB/LN-like pathology, transmission of pathologic α-synuclein aggregates, mitochondria impairments, and neuronal toxicity, as well as amyloid-β fibrils-induced neurotoxicity in primary neurons. Strikingly, administration of GQDs can restore the behavioral deficits, LB/LN-like pathology and loss of DA neurons in α-synuclein PFFs induced α-synucleinopathy in vivo. Taken together, the discovery of GQD as a potential therapeutic agent provides a promising new treatment for PD and AD as well as other multiple neurodegenerative diseases related toα-synuclein and amyloid-β.