Background: Dose-response relationships between physical activity and metabolic syndrome (MetS) by sex and age are unclear. Purpose: We examined the associations of different intensities of physical activity with MetS by sex and age group. Methods: We analyzed 17,614 (56.5% women) adults from the Korean National Health and Nutrition Examination Survey, 2016-2018. Self-reported minutes per week of activities by intensity (walking, moderate, vigorous) were categorized by dose. Associations of activity intensities with MetS and its components were analyzed using one-way ANOVA and multinomial logistic regression models. Results: There were distinct patterns of associations of moderate-to-vigorous physical activity (MVPA) and walking categories with the MetS components by sex and age groups. Walking, moderate, and vigorous activities were associated with lower odds of MetS (independent of sex, age, and other covariates) in the highest category ([greater than or equal to]225 min/week) when compared with the lowest category (<10 min/week) by 12%, 30%, and 40%, respectively. Discussion: MVPA and walking were favorably associated with MetS, but the associations varied by sex, age, and the intensity of physical activity. Translation to Health Education Practice: Our findings would be pragmatic for health education in providing evidence on the dose-response relationship between physical activity and cardiometabolic risk factors.