Purpose: Oxidative stress plays an important role in the pathogenesis of chronic metabolic diseases. This study investigated the effect of the antioxidant-rich dietary intervention on oxidative stress, metabolic parameters, and arterial stiffness in elderly Koreans with metabolic syndrome (MetS). Materials and Methods: Thirty-one subjects with MetS were enrolled and randomly divided into dietary intervention group and control group. Subjects in the intervention group received three meal boxes prepared with antioxidant-rich ingredients every day for 4 weeks, and subjects in the control group maintained their usual diets. Anthropometric and various biochemical parameters related to oxidative stress, inflammation, and MetS were assessed. Brachial-ankle pulse wave velocity (baPWV) and fat measurement using computed tomography were also conducted before and after 4 weeks. Results: There were significant differences in waist circumference, visceral to subcutaneous fat ratio, lipid peroxidation, oxidized low density lipoprotein (oxLDL), systolic and diastolic blood pressure, lipid parameters, advanced glycation end products, and baPWV between before and after the study in the experimental group (all p<0.05). Significant inter-group differences were observed between the experimental and control group in terms of the differences in body mass index, waist circumference, oxygen radical absorbance capacity, protein carboxylation, lipid peroxidation, oxLDL, blood pressure, lipid parameters, and baPWV between before and after the study (all p<0.05). Conclusion Antioxidant-rich dietary intervention for a 4-week period ameliorated the state of oxidative stress and improved the components of MetS including central obesity, dyslipidemia, hypertension, and arterial stiffness in elderly Koreans with MetS.