Aim: To estimate psychiatric comorbidity in childhood onset immune-mediated inflammatory diseases (IMID).MethodsThe PRISMA guidelines were followed, and the protocol was registered at Prospero (ID: CRD42021233890). Literature was searched in PubMed, PsycINFO and Embase. Original papers on prevalence rates of diagnosed psychiatric disorders and/or suicide in paediatric onset inflammatory bowel disease (pIBD), rheumatic diseases (RD) and autoimmune liver diseases were selected. Pooled prevalence rates of psychiatric disorders (grouped according to ICD-10 criteria) within the various IMID were calculated using random-effects meta-analysis. Risk of bias was evaluated by the Newcastle-Ottawa scale.ResultsTwenty-three studies were included; 13 describing psychiatric disorders in pIBD and 10 in RD. Anxiety and mood disorders were mostly investigated with pooled prevalence rates in pIBD of 6% (95% confidence interval (CI): 4%–9%) and 4% (95%CI: 2%–8%), respectively, in register-based studies, and 33% (95%CI: 25%–41%) and 18% (95%CI: 12%–26%), respectively, in studies using psychiatric assessment. In RD, rates were 13% (95%CI: 12%–15%) for anxiety disorders and 20% (95%CI: 15%–26%) for mood disorders based on psychiatric assessment.ConclusionAnxiety and depression are commonly reported in childhood onset IMID. Physicians should be attentive to mental health problems in these patients as they seem overlooked.