The extensive use of various electronic games and communication devices, particularly among children and adolescents, has raised concerns, particularly during the COVID-19 pandemic. This study investigated the link between screen time and internalizing disorders, such as anxiety and depression, among individuals aged ≤18 during the global COVID-19 pandemic. This systematic review aims to summarize scientific publications from 2019 to early 2022 by searching databases, including the Cochrane Library, PubMed, Web of Science, Scopus, and PsycINFO, to identify suitable studies. In each paper, we searched the following keywords and their synonyms: screen, child, high school, middle school, and psychiatric disorders. The quality of the selected papers was evaluated using a checklist recommended by the National Institutes of Health (NIH) for observational cohort studies. Out of 986 reports identified, we included 12 papers with 14,483 participants. The study revealed a negative correlation between screen time (TV, computer, video games, and mobile phones) and behavioral outcomes. Smartphones were the most frequently used devices, with video games being more prevalent among older participants for education, communication, and entertainment purposes. The prevalence of depression ranged between 10% and 25%. Furthermore, anxiety and depression were identified as predictors of increased screen usage. Some results displayed variation based on the type of screen exposure, the questionnaires used, and the age of the participants. The findings imply an indirect association between increased screen time and depression and anxiety. It is crucial to consider limitations on screen time exposure and parental supervision as measures to prevent certain mental disorders.