Objectives: Obesity and oral diseases among children are growing worldwide public health problems due to their adverse impact on the growth and development of children. The objective of this study was to determine the correlation between obesity and oral health in schoolchildren. Methods: Data from the National Health and Nutrition Examination Survey 2017-2018 was used for this study. Based on WHO criteria, the body mass index (BMI) was classified into underweight, normal weight, overweight, and obesity groups. The oral health outcomes were also dichotomized as being either satisfactory or unsatisfactory. First, descriptive statistics for the sample were calculated. Next, we used the Chi-square test to compare proportions of groups. All analyses were performed with SPSS v28 and statistical significance was set at p < 0.05. Results: The total sample was 28,872,606 children of age group 6 to 12 years with an average age of 9.07 years (SD=1.96). There was approximately equal distribution of males and females. Respondents were primarily non-Hispanic white (49%) and came from low-middle income families (49.2%). The prevalence of underweight, normal, overweight, and obesity for all was 56%, 33.4%, 7.7%, and 3%, respectively. More boys were skinny (58.9% vs. 52.9%) and overweight (8.2% vs. 7.1%) than girls. In comparison, obesity was slightly higher in girls than boys (3.6% vs. 2.3%). The overall prevalence of unsatisfactory oral health was 11.6%, with a lower prevalence among girls than boys (8.7% vs. 14.3%, P < 0.05). Unsatisfactory oral health of children belonged to underweight, normal, overweight, and obesity was 9.9%, 14.7%, 13.9%, and 8.8%, respectively. With increasing BMI levels, the prevalence of unsatisfactory oral health decreased (P<0.05). Conclusions: Obesity is negatively correlated with poor oral health among schoolchildren. It is necessary to further investigate how diet and oral hygiene habits influence the association between BMI and oral health.