BACKGROUND: This study aimed to analyze the parental socio-demographic characteristics of children and adolescents aged 9 to 18 years old, as well as the living and housing conditions associated with the psychological distress in these two sub-populations during and after France's first national COVID-19-related lockdown in spring 2020. METHODS: We used data from the cross-sectional, observational, web-based study CONFEADO, which collected data on children and adolescents" living and housing conditions and socio-demographic characteristics as well as those of their parents. It also collected data on children's and adolescents" health behaviors and psychological distress. We assessed psychological distress using the 10-item Children and Adolescents Psychological Distress Scale (CAPDS-10), and performed a multinomial logistic regression. RESULTS: A total of 2882 children and adolescents were included in the present study. Factors associated with moderate psychological distress included being a female, parental financial difficulties, a lack of a private living space at home for the child/adolescent, and the following child health behaviors: no leisure or recreational activities with adults in the household, doing less than one hour of school homework a day, and not going outside during the lockdown. Severe psychological distress was associated with the parent's occupation (especially essential frontline workers), a lack of a private living space at home for the child/adolescent, and the following child health behaviors: spending over 5 h a day on social media, doing less than one hour of school homework a day, and no leisure or recreational activities with adults in the household. CONCLUSIONS: This study emphasizes the impact of housing and living conditions, as well as parents" socio-economic characteristics on children's health behaviors and psychological needs during the first COVID-19-related lockdown in France. Our results suggest that health policies implemented during future pandemics should consider these structural social determinants to prevent severe psychological distress in children and adolescents.