The COVID-19 pandemic has forced children to spend increased amounts of time at home resulting in adverse effects on their physical and psychosocial wellbeing. Parents need to be aware about the changes in the mental and physical health of the children. Objectives: To identify the physical and mental health problems the children are facing because of the lockdown and to assess the awareness of such problems amongst the parents. Design: A cross sectional online survey was conducted to assess the impact of COVID-19 on physical and mental health of the children from parents' perspectives. Setting: Mumbai, Maharashtra, India Main Outcome Measure: Parent reported questionnaire. Results and conclusion: There were a significant increase in the number of hours spent on mobile phones, sitting, and sleeping during the lockdown as compared to before the lockdown whereas the number of hours spent on physical activity significantly decreased and also impacted their mental health. By taking part in the survey, the parents of the children became aware of the changes occurring in their child. These findings can guide immediate programmatic and policy efforts to preserve and promote child health during the COVID-19 outbreak and crisis recovery period, and to inform strategies to mitigate potential harm during future pandemics.