AbstractOxidative stress plays a crucial role in neurodegenerative diseases like Parkinson's and Alzheimer's. Studies indicate the relationship between oxidative stress and the brain damage caused by a high‐fat diet. It is previously found that a lupin protein hydrolysate (LPH) has antioxidant effects on human leukocytes, as well as on the plasma and liver of Western diet (WD)‐fed ApoE^−/− mice. Additionally, LPH shows anxiolytic effects in these mice. Given the connection between oxidative stress and anxiety, this study aimed to investigate the antioxidant effects of LPH on the brain of WD‐fed ApoE^−/− mice. LPH (100 mg kg⁻¹) or a vehicle is administered daily for 12 weeks. Peptide analysis of LPH identified 101 amino acid sequences (36.33%) with antioxidant motifs. Treatment with LPH palliated the decrease in total antioxidant activity caused by WD ingestion and regulated the nitric oxide synthesis pathway in the brain of the animals. Furthermore, LPH increased cerebral glutathione levels and the activity of catalase and glutathione reductase antioxidant enzymes and reduced the 8‐hydroxy‐2’‐deoxyguanosine levels, a DNA damage marker. These findings, for the first time, highlight the antioxidant activity of LPH in the brain. This hydrolysate could potentially be used in future nutraceutical therapies for neurodegenerative diseases.