Abstract Background School-aged children are recommended to complete at least one hour of moderate to vigorous intensity physical activity per day. North American data has shown that due to COVID-19 restrictions placed on in person schooling and extracurricular activities, children were not meeting recommended levels of physical activity. Additional barriers to activity during the first wave of the COVID-19 pandemic included lack of access to public facilities including community centers, parks, and outdoor recreation. Decreased physical activity in children has been shown to have a negative impact on both physical and mental health, and childhood development. However, there is a paucity of literature on parents’ perceptions of the association between physical activity and physical and mental health. Objectives The objective of this study was to gain a better understanding of the implications of the COVID-19 pandemic on levels of physical activity and parents’ perceptions surrounding physical activity and physical and mental health. Design/Methods An online survey was distributed to parents of school-aged children aged 4-13 in Ontario. The survey included questions regarding demographics, children’s physical activity prior to and during the first wave of the COVID-19 pandemic, and parental perceptions regarding the pandemic’s impact on mental and physical health. This study received ethics approval, was hosted on the REDCapTM platform, and distributed from February-June 2021 through a local school board, the Pediatrics section of the Ontario Medical Association, and through social media. Results Of 361 participants, 90.4% strongly agreed that physical activity was important for mental health, and 92.2% strongly agreed that physical activity was important for physical health. There was a statistically significant decrease in the overall mean number of hours of physical activity per week between pre-COVID and the first wave of COVID (mean difference = 9.34 hours, SD = 10.06, p<0.001). Additionally, parents of children with decreased physical activity reported a statistically significant negative impact on physical and mental health as compared to parents whose children had no change in amount of physical activity. Decreased energy, poor sleep, increased anxiety, mood disturbances, and disruptive behaviour were noted by over 50% of respondents. Conclusion This survey highlights that parents themselves perceived a significant negative impact on children’s mental and physical well-being with decreased physical activity during the COVID-19 pandemic. This emphasizes the importance of retaining access to recreational facilities and extracurricular activities. Future research includes identifying ways to re-engage parents and children with physical activity during times of decreased access.