Abstract Objective Research has highlighted the potential adverse effects of weight bias internalization (WBI) on adolescents, but there has been little examination of WBI and sources of weight teasing (family, peers, or both) or across racial/ethnic diversity of adolescents. We aimed to examine the relationship between WBI and sources of weight teasing across sociodemographic characteristics and weight status in a diverse community sample of adolescents. Methods Data were collected from a U.S. sample of 1859 adolescents aged 10–17 years (59% female; 43% White, 27% Black or African American, and 25% Latino). An online questionnaire was used to assess participants’ experiences of weight teasing from family members, peers, or both, and their weight status, weight-related goals, WBI, and sociodemographic characteristics. Results Adolescents experiencing weight teasing from both family and peers reported the highest levels of WBI, while those reporting no teasing exhibited the lowest levels. These patterns were observed across sex, race/ethnicity, weight status, and weight goals, and persisted after controlling for depressive symptoms. Notably, family influences played a salient role, with adolescents reporting higher WBI if teased by family only compared to teasing from peers only. Sex and racial differences were also observed in adolescents’ experiences with weight-based teasing. Conclusion Our study reveals associations between adolescent weight-based teasing, WBI, and sociodemographic factors. Weight-based teasing, whether from family and peers or from family only, was associated with increased WBI. Interventions targeting weight stigma in youth should not be limited to peer-focused efforts, but should also emphasize supportive family communication.