BACKGROUND: During the current ongoing COVID-19 pandemic, psychological problems like anxiety, depression, irritability, mood swings, inattention and sleep disturbance are fairly common among quarantined children in several studies. A systematic review of these publications to provide an accurate burden of these psychiatric/behavioral problems is needed for planning mitigating measures by the health authorities. METHODS: Different electronic databases (MEDLINE, EMBASE, Web of Science, CENTRAL, medRxiv and bioRxiv) were searched for articles describing psychological/behavioral complications in children/adolescents with/without pre-existing behavioral abnormalities and their caregivers related to the COVID-19 pandemic. Only original articles with/without comparator arms and a minimum sample size of 50 were included in the analysis. The pooled estimate of various psychological/behavioral problems was calculated using a random-effect meta-analysis. RESULTS: Fifteen studies describing 22 996 children/adolescents fulfilled the eligibility criteria from a total of 219 records. Overall, 34.5%, 41.7%, 42.3% and 30.8% of children were found to be suffering from anxiety, depression, irritability and inattention. Although the behavior/psychological state of a total of 79.4% of children was affected negatively by the pandemic and quarantine, at least 22.5% of children had a significant fear of COVID-19, and 35.2% and 21.3% of children had boredom and sleep disturbance. Similarly, 52.3% and 27.4% of caregivers developed anxiety and depression, respectively, while being in isolation with children. CONCLUSION: Anxiety, depression, irritability, boredom, inattention and fear of COVID-19 are predominant new-onset psychological problems in children during the COVID-19 pandemic. Children with pre-existing behavioral problems like autism and attention deficit hyperactivity disorder have a high probability of worsening of their behavioral symptoms.