Childhood obesity has become a global epidemic. Childhood obesity has many long-term adverse effects on morbidity and mortality. The prevalence of end-stage renal disease (ESRD) has risen dramatically in the past decade in parallel with the increase in obesity. Our current understanding of the consequences of childhood obesity on kidney function and disease is very limited. The present study presents the worldwide trends in childhood obesity and reviews published studies that have examined the association between obesity and kidney disease in the pediatric and adult populations. A large number of studies have been conducted to examine the association between obesity and kidney disease in general adult populations; however, few have been conducted to examine the impact of childhood obesity on the risk of kidney disease. Findings from large cohort studies in adult general populations show that obesity increases the risk of kidney diseases. Six follow-up studies in pediatric patients were identified, and they indicate that childhood obesity is associated with an increased risk of kidney disease and the progression and mortality of kidney disease. Future studies in the pediatric populations are needed.