The psychological impact of the COVID-19 pandemic has been widely discussed during the past few months, with scholars expressing concern about its potential debilitating consequences on youth mental health. Hence, this research aimed to provide a systematic review of the evidence on the COVID-19 pandemic’s impact on youth mental health. We conducted a mixed methods integrated review to identify any empirical study that focused on young people ≤ 18 years old. Eight databases were systematically searched to identify studies of any type of research design. The selection procedure followed the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines. The protocol of this systematic review was registered with PROSPERO (protocol ID: CRD4202019375). Twelve studies deemed eligible for data extraction (n = 12,262). The findings show that COVID-19 has an impact on youth mental health and is particularly associated with depression and anxiety in adolescent cohorts. The quality appraisal indicated that all studies were of low or moderate methodological quality. The COVID-19 pandemic is affecting young people’s lives, and thus generating robust research evidence to inform policy decisions is essential. Hence, the methodological quality of future research should be drastically improved.