Hyperhomocysteinemia (HHcy)-related brain vascular disorders and brain endothelial dysfunction are important characteristics of the pathogeneses of subarachnoid hemorrhage and stroke. Upregulated homocysteine (Hcy) can impair the integrity of the blood-brain barrier (BBB). Opicapone has been recently licensed for the management of Parkinson's disease (PD); however, it is unknown whether it possesses a protective effect in brain vessels against HHcy. To investigate the beneficial effects of Opicapone on BBB permeability against HHcy, we carried out both in vivo and in vitro experiments. Mice were allocated into four groups: the Control, Opicapone, HHcy, and HHcy + Opicapone. Interestingly, we found that the administration of Opicapone attenuated the increased BBB permeability in Hcy-treated mice, as determined by sodium fluorescein staining. The immunofluorescence staining showed that Opicapone prevented homocysteine-induced reduction of claudin-2 in the mice cortices. The in situ zymography assay revealed that Opicapone suppressed homocysteine-increased matrix metalloproteinases (MMPs) activity in the cortices. In bEnd.3 brain endothelial cells, Opicapone treatment ameliorated homocysteine-induced lactate dehydrogenase (LDH) release and expression of matrix metalloproteinase-2 (MMP-2) and matrix metalloproteinase-9 (MMP-9). Furthermore, Opicapone alleviated homocysteine-induced decrease in claudin-2 level in bEnd.3 cells. In summary, our results show that Opicapone protects against HHcy-induced BBB permeability by reducing the expression and gelatinase activity of MMPs, and increasing the expression of claudin-2.