Purpose This study aims to explore the associations between weight status, body image dissatisfaction (BID), and psychosocial adjustment [quality of life (QOL), internalizing and externalizing problems] of normal-weight and obese youth. It aims to explore whether the associations between weight status and psychosocial adjustment are mediated by BID as well as the moderating role of youth's age and gender on these associations. Methods The sample comprised 260 children and adolescents aged 8-18 years with normal weight (n = 128) and obesity (n = 132). All of the participants completed self-report instruments, including the KIDSCREEN-10, Strengths and Difficulties Questionnaire, and Collins Body Image scale. Results Obese youth, regardless of gender, reported poorer QOL, more internalizing/externalizing problems, and higher rates of BID compared with their normal-weight counterparts. BID mediated the relationship between weight status and QOL, but only for youth above 12-year old. The relationship between weight status and internalizing/externalizing problems was direct and independent of youth's age and gender. Conclusions Pediatric obesity is associated with poorer psychosocial outcomes, which underlines the need for preventive and early interventions. An important target in psychological interventions seems to be BID, which proved to be an important mechanism linking obesity and decreased QOL among adolescents.