PurposeTo identify the prevalence and predictive factors of body image dissatisfaction among Chinese adolescent and young adult (AYA) survivors of sarcoma and to evaluate its associations with behavioral outcomes.MethodsIn total, 116 AYA survivors (response rate: 88%; 48.3% female; mean age 28.2 years, SD = 8.2 years) of osteosarcoma (49.1%) or soft‐tissue sarcoma (50.9%) were recruited from an academic hospital. The survivors self‐reported their perceived body image using the Body Image Scale. Behavioral outcomes were assessed using DSM‐oriented scales of the ASEBA Adult Self‐Report checklist. Multivariable linear regression was conducted to identify predictors of body image perception and to investigate the association between body image dissatisfaction and behavioral outcomes (adjusted for clinically relevant variables and corrected for false discovery rate). Mediation analyses were performed to examine the mediating effects of body image perception between clinical, treatment, or socioenvironmental risk factors and behavioral outcomes.ResultsAt 15 years post‐cancer diagnosis, one‐third of the cohort (39.7%) reported dissatisfaction with their body image. The significant risk factors associated with body image dissatisfaction were being female (standardized coefficient estimate [Est] = 0.21, SE = 0.10; p = 0.047), surgery treatment (Est = 0.19, SE = 0.09; p = 0.046), and worse family functioning (Est = 0.27, SE = 0.10, p = 0.013). Body image dissatisfaction was associated with symptoms of depression (Est = 0.30, SE = 0.10; p = 0.005) and avoidant personality problems (Est = 0.37, SE = 0.11; p < 0.001). Negative body image perception significantly mediated the association between poor family functioning and avoidant personality problems (proportion‐mediated 26.3%, p = 0.038).ConclusionBody image dissatisfaction was associated with more significant internalizing symptoms of depression, anxiety, and avoidant personality. A negative body image perception may mediate the association between poor family functioning and psychological distress among adult survivors. The provision of psychosocial intervention early during the cancer care continuum may mitigate the negative impact of body image distress in Chinese AYA survivors.