BACKGROUND: Sexual orientation discrimination increases the risks of negative health outcomes for sexual minorities. Previous studies have found increased rates of eating disorder symptoms in sexual minority individuals, which is attributable to minority stress and discrimination that they experience. Emerging research suggests relationships between sexual orientation discrimination and eating disorder symptoms. However, there is a lack of studies focusing on early adolescents. The objective of this study was to determine prospective associations between discrimination based on sexual orientation and eating disorder symptoms in a national sample of 10-13-year-old early adolescents in the U.S. METHODS: We examined prospective data from Year 2 (2018-2020) and Year 3 (2019-2021) of the Adolescent Brain Cognitive Development (ABCD) Study (N = 8976). Multiple logistic regression analyses were used to estimate associations between self-reported experiences of sexual orientation discrimination in Year 2 and eating disorder symptoms in Year 3, adjusting for potential confounders, including eating disorder symptoms in Year 2. Sexual orientation discrimination was assessed based on the Perceived Discrimination Scale, which measures adolescents perception of being treated unfairly based on various sociodemographic characteristics. Eating disorder symptoms were based on the parent-reported Kiddie Schedule for Affective Disorders and Schizophrenia (KSADS-5). RESULTS: In this demographically diverse sample of early adolescents (N = 8976, age range 10-13 years at Year 2), 5.5% of adolescents reported sexual orientation discrimination in Year 2. The prevalence of parent-reported eating disorder symptoms in Year 3 varied from 1.0 to 8.3%. In the adjusted models, sexual orientation discrimination was prospectively associated with worry about weight gain (adjusted odds ratio [aOR] 2.33, 95% confidence interval [CI] 1.15-4.69) and self-worth tied to weight (aOR 1.60, 95% CI 1.01-2.53) one year later. CONCLUSIONS: Early adolescents who have experienced sexual orientation discrimination have higher odds of experiencing eating disorder symptoms, particularly worrying about weight gain and tying self-worth to weight. Clinicians may consider screening for sexual orientation discrimination and providing affirmative, trauma-informed care when evaluating and treating even younger sexual minority adolescents for eating disorder symptoms.