Background: Obesity is a health problem that is often found in children. In Indonesia, many children are overweight and obese. Mothers who have wrong perception about child’s weight status and have poor knowledge about child obesity usually have obese children. Hence, mother’s perception and knowledge influence the children’s weight status. Aim: To identify mother’s perception and knowledge about obesity in pre-school children in Indonesia. Methodology: This study used quantitative descriptive method with univariate data analysis technique. The sample is 408 mothers who have pre-school age children in Indonesia, with incidental sampling technique as the sampling method. This study used questionnaire about mother’s perception and knowledge towards obesity in preschool age children with validity and reliability values of 0,739 and 0,747. Result: 223 mothers (54.7%), had negative perceptions about obesity in preschool age children and 276 mothers (67.6%) had high level of knowledge about obesity in preschool age children. Recommendation: The results of this study can be used by educational institutions to increase mother’s knowledge about child obesity through education. It also can be used as reference for further research on childhood obesity with different variables, such as mother’s attitudes about child obesity and children’s eating habits