Background: Body mass index (BMI) and dental caries among adolescents is a growing worldwide public health issue. They share some common and modifiable influences. The objective of this study was to evaluate the association between BMI and dental caries among adolescents in the United Arab Emirates (UAE). Methods: This cross-sectional study enrolled 478 adolescents 13-19 years old from private and public schools in the UAE. Participants were classified as underweight, normal weight, overweight, and obese. Dental caries was diagnosed according to the criteria recommended by the World Health Organization (WHO). Independent t-tests were used to compare average number of decayed, filled and missing surfaces (DMFS) by age, sex, school type, mothers’ employment, BMI categories, fruit and vegetable intake (F/V intake) and plaque index. Additionally, a multiple linear regression model was applied to analyze the association between BMI categories and dental caries, adjusted for confounding factors considered in this study. Results: The average age of the participants was 16.2 ± 1.4. Prevalence of underweight, normal, overweight, and obesity was 14.6%, 46.4 %, 17.6%, and 21.4%, respectively. Overall, the average DMFS score was 4.35 ± 4.5, with lower dental caries rates among girls than boys. The linear regression model revealed that, being a male, attending a public school and being underweight were all positively and significantly associated with dental caries. Conclusions: Underweight is associated with dental caries among adolescents in the UAE. Further research is required to investigate the complex association between obesity and dental caries and how dietary habits, oral hygiene habits, and parental socioeconomic status mediate the association between BMI and dental caries.