Introduction: Overweight/obese children have postural control differences compared with normal-weight children. Nevertheless, there are not studies that analyze the effect of obesity during the entire period comprised between childhood and adolescence. The objective of this study was to determine the differences in postural control between normal-weight and overweight/obese participants during early and middle childhood and adolescence. Methods: 359 children were divided into six groups according to age and weight status. Each participant carried out one 30-s trial with eyes open (EO) and one 30-s trial with eyes closed (EC). Center of pressure signals were acquired using a Wii Balance Board. Mean velocity in antero-posterior (MVAP) and medio-lateral (MVML) directions and the 95% confidence interval ellipse area were calculated. Results: A Mann Whitney U-test showed significant differences between normal-weight and obese 8- to 12-year-old children in MVAP and MVML in both EO and EC. In 13- to 17-year-old adolescents, there were differences between normal-weight and overweight/obese in ellipse area and MVML, both in EO and EC condition. There were no differences in postural stability between normal-weight and overweight/obese 4- to 7-year-old children. Conclusions: Obesity reduces postural stability only in middle childhood and adolescence but not in early childhood.