To investigate the association between functional constipation, infant feeding in early infancy and eating behavior in preschool children. A cross-sectional study was undertaken in public and private schools in the state of Sergipe (Northeast of Brazil). The sample calculation was based on a 25% estimate of constipation prevalence in Brazilian children, resulting in a sample size of 1051 children. Functional constipation was assessed using Rome IV criteria. Eating behavior was assessed using the Children's Eating Behavior Questionnaire. Adjusted odds ratios were estimated using a multivariate model. The prevalence of functional constipation was 23%. After adjusting for water intake, children with food fussiness were >6 times likely to have constipation (odds ratio [OR] = 6.65; 95% confidence interval [CI] 5.19-8.52). Children who were fed with cow's milk in the first 6 months of age were up to 15.2 times more likely to have functional constipation. Bottle feeding at 0-6 months of age increased the risk of functional constipation at preschool age (whole cow's milk: OR = 17.02; 95% CI 7.33-39.51, infant formula: OR = 6.35; 95% CI 3.42-11.79, mixed breastfeeding: OR = 10.83; 95% CI 4.57-25.69). Food fussiness and the use of cow's milk-based feeding bottles at 0-6 months of age were associated with functional constipation in preschool children.