BACKGROUND: Hikikomori, or prolonged social withdrawal, is a clinical condition usually emerging during adolescence or young adulthood, characterized by severe self-isolation in one's home, and often associated with other psychiatric disorders and symptoms. OBJECTIVE: The study summarized evidence of hikikomori diagnostic criteria, clinical manifestations, and comorbidity with psychiatric disorders and symptoms in adolescents and young adults. METHODS: A scoping review was conducted following PRISMA guidelines, with four electronic databases searched for original works in English, French, and Italian published since 2010. RESULTS: A total of 15 studies were selected, 7 involved adolescents, 4 young adults, and 4 participants from both age groups. Most studies relied on the diagnostic criteria proposed for hikikomori inclusion in the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5). Differences in hikikomori and comorbidity profiles were identified between adolescents and young adults. CONCLUSIONS: Heterogeneity characterized hikikomori diagnostic criteria, comorbidity, demographic and clinical features of the study samples. Studies adopting more homogeneous populations, shared diagnostic criteria, consistent assessment tools and longitudinal designs are needed to better clarify the clinical features of hikikomori in young people.