The purpose of the study was to identify the economic differences in familial, physiological, psychological, and lifestyle characteristics associated with overweight and obese children in South Korea. A total of 407 overweight and obese children participated in the study. The obesity rate was 69.0% and the prevalence of metabolic syndrome (MS) was 33.3% in the low-income bracket, and the prevalence of MS was 27.2% for the population. The children in the low-income group were more prone to have poor eating behavior and more likely to spend more than 2 hr viewing television. They also were more likely to have lower self-esteem and more depressive symptoms. School nurses should understand that risk factors for childhood obesity are more prevalent in low-income groups, which will eventually aggravate health disparities between socioeconomic status groups. Therefore, prevention programs for childhood obesity, which target high-risk groups of such children need to be developed and prioritized.