Background Properly fitted shoes can support the development of growing feet and prevent problems and pathologies, not only in childhood, but also in adulthood. This points to the need to conduct research on the impact of shoe fitting on the structure of the foot in order to raise awareness and importance of this problem, to enable proper decisions regarding the purchase and use of shoes. The aim of this study was to analyze indoor footwear fit and its impact on foot structure in 7-year-old schoolchildren. Methods The CQ-ST podoscope and the Clevermess device were used for measurements. The analysis was carried out using the Mann Whitney U test, Wilcoxon signed-rank test, Chi-square test, regression analysis. Results About 40% of girls and boys had shoes that were incorrectly fitted in length, while as many as 74% of girls and 66% of boys wore shoes that were incorrectly fitted in width. Regression analysis demonstrated a statistically significant influence of the footwear length on longitudinal arch of the right and left foot and the transverse arch of the right foot. In boys, the length of the shoes shows associations with the right and left hallux valgus angle. Conclusion A significant percentage of the studied 7-year-olds, regardless of gender, wears inappropriately fitted shoes. In both sexes, the length of the footwear influenced the longitudinal arch of the right and left foot and the transverse arch of the right foot. Due to the deformity of the first metatarsophalangeal joint, the boys with hallux valgus require footwear which is wider and therefore their shoes need to be bigger in size.