Background: Parkinson’s disease (PD) is a neurodegenerative disorder characterized by dopaminergic neuronal loss, oxidative stress, and elevated monoamine oxidase-B (MAO-B) activity. Polygonum cuspidatum, rich in antioxidant phytochemicals, has potential neuroprotective effects. Objective: To evaluate the anti-Parkinsonian and MAO-B inhibitory properties of Polygonum cuspidatum ethanolic extract (PCEE) in a 6-hydroxydopamine (6-OHDA) induced rat model of PD. Methods: Rats were divided into five groups: Sham control, 6-OHDA control, 6-OHDA + L-DOPA (6 mg/kg), and 6-OHDA + PCEE (200 and 500 mg/kg). Behavioral assessments (rotarod, catalepsy, and apomorphine-induced rotations) and biochemical analyses (MAO-B activity, dopamine levels via HPLC, lipid peroxidation, catalase, and glutathione levels) were performed. Results: 6-OHDA induced significant motor deficits, elevated MAO-B activity, reduced dopamine, increased lipid peroxidation, and decreased antioxidant enzyme activities. PCEE treatment produced a dose-dependent improvement in motor behavior and significantly inhibited MAO-B activity. Additionally, PCEE restored dopamine levels and antioxidant status, reducing oxidative damage comparable to L-DOPA. Conclusion: Polygonum cuspidatum ethanolic extract exhibits potent anti-Parkinsonian effects through MAO-B inhibition and antioxidant mechanisms, suggesting its potential as a natural therapeutic agent for PD management.