Aging is associated with increased body fat and lower lean body mass, which leads to increased prevalence of obesity and metabolic syndrome. This study aimed to investigate the association of regular participation in walking and body mass index (BMI) with metabolic syndrome and its 5 criteria in elderly Koreans. A total of 3554 (male = 1581, female = 1973) elderly subjects (age ≥ 65 years), who participated in the Fifth Korea National Health and Nutrition Examination Survey (KNHANES V) were analyzed in this cross-sectional study. Participation in walking activity, BMI, metabolic syndrome and its 5 criteria; waist circumference (WC), systolic blood pressure (SBP), diastolic blood pressure (DBP), fasting glucose (FG) levels, triglyceride (TG) levels, and high-density lipoprotein cholesterol (HDL—C) levels, were measured. Subjects were categorized into four groups based on the duration and regularity of their walks and BMI. In the regular walking (≥30 min of continuous walking a day, on ≥5 days a week) and normal weight (BMI < 23 kg/m2) group, WC, SBP, DBP, FG, and TG levels were significantly lower, and HDL-C levels were significantly higher, compared to the non-regular walking and overweight (BMI ≥ 23 kg/m2) group. Furthermore, the odds of metabolic syndrome was 4.36 times higher (Odds ratio [OR]: 4.36, 95% confidence interval [CI]: 3.37–5.63) in the non-regular walking and overweight group than that of the regular walking and normal weight group after controlling for the influence of age, sex, and smoking status. Moreover, The BMI (β = 0.328, R2 = 0.152) were more contributing factors than Regular walking (β = −0.011) for metabolic syndrome. In conclusions, regular participation in walking activity and implementing weight control may reduce the incidence rate of metabolic syndrome in elderly Koreans, with weight management serving as the greater influences of the two.