Metabolic syndrome (MetS) is increasingly reported in children, mainly in the presence of overweight/obesity. From the most recent report, up to 60% of overweight and obese children can be affected by this syndrome. MetS acquired during childhood has been shown to track into adulthood, including its clinical complications, such as type 2 diabetes and cardiovascular diseases. Among the practical preventive and therapeutic measures to be taken in children, physical activity (PA) appears to be at least as efficient as the most adequate pharmacology. The current literature suggests that exercise programs based either on aerobic-or resistance-type exercises, or a combination of these 2 types of structured activity, may promote insulin sensitivity and weaken or suppress MetS in children. Furthermore, daily-living activities such as brisk walking were found to substantially reduce the risk of MetS among children. Regardless of their weight status, PA needs to be promoted among children as early as possible.