Food insecurity and obesity coexist among children and families. We examined the association between receipt of plant-based family food packages from the Massachusetts General Hospital Revere Food Pantry and change in body mass index (BMI), adjusted for age and sex, among children during the COVID-19 pandemic. Among 35 children aged 2 to 18 years who received the packages between January 2021 and February 2022, we observed a change in BMI of -0.04 kg/m2 (95% CI, -0.08 kg/m2 to -0.01 kg/m2) for each package received. Our results suggest plant-based food packages might mitigate, and potentially reverse, BMI increase in children in households seeking food assistance.