Abstract Background Children are susceptible to the food environment. This research assessed changes in retail food environments near schools in Flanders between 2008 and 2020 and associations with children’s and adolescents’ weight status. Methods The food environment within a 500 m and 1000 m road network distance to all primary and secondary schools was mapped using spatial indicators. The commercial Locatus database, including addresses of all food retailers in Flanders, was used to calculate the density of different types of food retailers near the school perimeter, the percentage of schools with at least one food retailer of a certain type near the school perimeter and the shortest distance from the school entrance to the nearest food retailer of a certain type. A generalized linear model was used to explore associations between these indicators and the percentage of children and adolescents with overweight at the school level. Results Food environments near schools in Flanders were found to be unhealthy in 2020, with a significant increase in fast food restaurants and convenience stores between 2008 and 2020. The density of fast food restaurants within a 1000 m walking distance from primary and secondary schools increased from 5.3 ±0.3 to 6.3 ±0.4 and from 10.2 ±0.7 to 12.7 ±0.9 respectively between 2008 and 2020, while the density of convenience stores increased from 3.2 ±0.3 to 3.8 ±0.4 and from 6.2 ±0.6 to 7.6 ±0.8 respectively. Food environments near schools with a higher proportion of children from a poor socio-economic background were found unhealthier, regardless of the urbanization level. A significant positive association was found between the density of fast food restaurants as well as the density of convenience stores around primary schools and the percentage of children aged < 6 years and 6–12 years with overweight. A positive, not significant association was found between the density of fast food restaurants as well as the density of convenience stores around secondary schools and the ...