Introduction In recent years, built environmental characteristics have been linked to childhood overweight, but the results remain inconsistent across studies. The present study examines associations between several built environmental features and body weight status (BMI) among a large sample of preschool children in the city of Hannover, Germany.Methods Walkability (index), green space availability and playground availability related to preschool children’s home environments was measured using the Geographic Information Systems (GIS) and data from OpenstreetMap (OSM). These built environment characteristics were linked to the data from the 2010-2014 school entry examinations in the Hannover city (n = 22,678), and analysed using multi-level linear regression models to examine associations between the built environment features and the BMI percentiles of these children (4-8 years old). Several socio-demographic factors were included in the analysis, including migration background, family structure and parental educational level. Results No significant associations of built environmental factors on children’s BMI were detected, but the effect between green space availability and BMI was modified by the parental educational level. In children with lower compared to higher educated parents, a higher spatial availability of greenspace was significantly associated with reduced body weight. Conclusion The finding of no overall association between the built environment and body weight could be due to misclassification in the presence of suboptimal variable reliability. However, the environmental effects may also be restricted to the less privileged children, which may indicate that built environmental features might have the potential to reduce health inequalities. Future research should continue to monitor the disparities in diverse built environment features and how these are related to children’s health.