Background & Aims: Child obesity is increasing in developing countries. This study assessed the prevalence of obesity and some related factors among less than 5-years children in Bandar Turkmen district, Iran. Methods: In this descriptive-analytical study, 616 children aged less than 5 years were selected with stratified random sampling. Obesity was defined as more than +2 standard deviation (SD) National Center for Health Statistics (NCHS) reference. Data were collected by interviewing mothers using a questionnaire and were analyzed with chi-square and Fisher’s tests and multiple regression logistic models. Results: 6 percent of children were obese. Prevalence of obesity did not differ significantly between boys and girls (6 and 6.1 percent respectively). Less than 2500 g and more than 4000 g birth weight (P = 0.031), less than 18 months breast feeding duration (P = 0.017), more than 37 years mother’s present age (P = 0.039), more than 30 years mother’s delivery age (P = 0.043), and formula or cow’s milk plus breast feeding up to 6 months of age (P = 0.018) had significant correlation with children’s obesity. Exclusively breast feeding up to 6 months of age rather than formula or cow’s milk plus breast feeding, reduced obesity risk about 2.45 times (P = 0.019). Conclusion: This study suggests that exclusively breast feeding at first 6 months of age, longer breast feeding duration and pregnancy in lower than 30 years of age reduce risk of child obesity.