The association between executive function and excess weight is becoming increasingly evident. However, the results of previous studies are still inconclusive, and there is a lack of evidence in early childhood. This study aims to examine the association between executive function, in terms of overall and subscales of executive function (e.g., inhibition, working memory, and shifting), and weight excess in preschoolers. A population-based cross-sectional study was conducted on children aged 2-5 years of age from public and private schools in Chiang Mai, Thailand. Participants' weights and heights were measured and classified into three weight status groups (i.e., children with normal weight, overweight, and obesity groups). Executive function was assessed using the parent-report Behavior Rating Inventory of Executive Function-Preschool (BRIEF-P). Multivariable polynomial regression was performed to analyze the association between executive function and weight status. A total of 1,181 children were included in the study. After adjusting for confounders, impaired overall executive function significantly increased the probability of being overweight (odds ratio [OR] = 2.47; 95% confidence interval [CI] 1.33 to 4.56). A similar trend of association was also found between impaired inhibition and overweight status (OR = 2.33; 95%CI 1.11 to 4.90). Furthermore, poor working memory was associated with both overweight and obesity (OR = 1.87; 95%CI 1.09 to 3.20 and OR = 1.74; 95%CI 1.09 to 2.78, respectively). Our data suggest that deficits in executive function, particularly inhibition and working memory, are associated with weight excess in preschoolers. Early promotion of executive function may be needed at this developmental age to prevent unhealthy weight status.