Background: The Coronavirus (COVID-19) pandemic has led to the enforcement of home confinement and the prolonging of school closures, indefinitely. There is a pressing need to call attention to the pandemic’s longer-term effect on children’s and adolescents’ health and well-being. The aim of this study was to assess the impact of the country-wide lockdown on dietary and lifestyle behaviours of adolescents in the West Bank, Palestine. Methods: The study was conducted on a sample of 600 adolescents (10-19 years old) in the West Bank, Palestine. Participants were selected for the study using randomly generated phone numbers and snowball sampling. Interviews were conducted by telephone to assess:dietary habits, physical activity, screen time, sleeping patterns, sources of stress and socio-demographics. Results: Among our sample, there was an increase in weight gain, food intake, consumption of non-nutritional foods, screen time and sleeping hours as well as a decrease or lack of physical activity in comparison to before the lock down. Weight gain was independently associated with increased food intake. Conclusion: Recognizing the adverse effects of the COVID-19 pandemic and integrating dietary and lifestyle programs into lockdown conditions and school closures is critical for adolescents’ long-term health.