ImportanceThe 5-item Sick, Control, One, Fat, Food (SCOFF) questionnaire is the most widely used screening measure for eating disorders. However, no previous systematic review and meta-analysis determined the proportion of disordered eating among children and adolescents.ObjectiveTo establish the proportion among children and adolescents of disordered eating as assessed with the SCOFF tool.Data SourcesFour databases were systematically searched (PubMed, Scopus, Web of Science, and the Cochrane Library) with date limits from January 1999 to November 2022.Study SelectionStudies were required to meet the following criteria: (1) participants: studies of community samples of children and adolescents aged 6 to 18 years and (2) outcome: disordered eating assessed by the SCOFF questionnaire. The exclusion criteria included (1) studies conducted with young people who had a diagnosis of physical or mental disorders; (2) studies that were published before 1999 because the SCOFF questionnaire was designed in that year; (3) studies in which data were collected during COVID-19 because they could introduce selection bias; (4) studies based on data from the same surveys/studies to avoid duplication; and (5) systematic reviews and/or meta-analyses and qualitative and case studies.Data Extraction and SynthesisA systematic review and meta-analysis was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guideline.Main Outcomes and MeasuresProportion of disordered eating among children and adolescents assessed with the SCOFF tool.ResultsThirty-two studies, including 63 181 participants, from 16 countries were included in this systematic review and meta-analysis. The overall proportion of children and adolescents with disordered eating was 22.36% (95% CI, 18.84%-26.09%; P < .001; n = 63 181) (I² = 98.58%). Girls were significantly more likely to report disordered eating (30.03%; 95% CI, 25.61%-34.65%; n = 27 548) than boys (16.98%; 95% CI, 13.46%-20.81%; n = 26 170) (P < .001). Disordered eating became more elevated with increasing age (B, 0.03; 95% CI, 0-0.06; P = .049) and body mass index (B, 0.03; 95% CI, 0.01-0.05; P < .001).Conclusions and RelevanceIn this systematic review and meta-analysis, the available evidence from 32 studies comprising large samples from 16 countries showed that 22% of children and adolescents showed disordered eating according to the SCOFF tool. Proportion of disordered eating was further elevated among girls, as well as with increasing age and body mass index. These high figures are concerning from a public health perspective and highlight the need to implement strategies for preventing eating disorders.