Background: Obesity and eating disorders commonly co-occur and might share common risk factors. Appetite avidity is an established neurobehavioural risk factor for obesity from early life, but the role of appetite in eating disorder susceptibility is unclear. We aimed to examine longitudinal associations between appetitive traits in early childhood and eating disorder symptoms in adolescence. Methods: In this longitudinal cohort study, we used data from Generation R (based in Rotterdam, the Netherlands) and Gemini (based in England and Wales). Appetitive traits at age 4–5 years were measured using the parent-reported Child Eating Behaviour Questionnaire. At age 12–14 years, adolescents self-reported on overeating eating disorder symptoms (binge eating symptoms, uncontrolled eating, and emotional eating) and restrictive eating disorder symptoms (compensatory behaviours and restrained eating). Missing data on covariates were imputed using Multivariate Imputation via Chained Equations. Ordinal and binary logistic regressions were performed in each cohort separately and adjusted for confounders. Pooled results were obtained by meta-analyses. Sensitivity analyses were performed on complete cases using inverse probability weighting. Findings: The final study sample included 2801 participants from Generation R and 869 participants from Gemini. Pooled findings after meta-analyses showed that higher food responsiveness in early childhood increased the odds of binge eating symptoms (odds ratio [OR] pooled 1·47, 95% CI 1·26–1·72), uncontrolled eating (1·33, 1·21–1·46), emotional eating (1·26, 1·13–1·41), restrained eating (1·16, 1·06–1·27), and compensatory behaviours (1·18, 1·08–1·30) in adolescence. Greater emotional overeating in early childhood increased the odds of compensatory behaviours (1·18, 1·06–1·33). By contrast, greater satiety responsiveness in early childhood decreased the odds of compensatory behaviours in adolescence (0·89, 0·81–0·99) and uncontrolled eating (0·86, 0·78–0·95) in adolescence. Slower eating ...