Data sources PubMed, Cochrane Library, and Google Scholar. Study selection Papers reporting a primary study in non-syndromatic preschool children aged 0-6 years, reporting body weight and dental caries experience as outcomes.Data extraction and synthesis Two reviewers independently screened the titles and abstracts of the identified citations for relevance. The full text articles were subsequently assessed for eligibility for both qualitative and quantitative review. Body weight outcomes were standardised into four groups; 'underweight' (BMI-for-age percentile less than five), 'normal weight' (BMI-for-age percentile between five and 85), 'overweight' (BMI-for-age percentile between 85 and 95), and 'obese' (BMI-for-age percentile greater than 95). Dental caries outcomes were based on decayed, missing, and filled teeth/surfaces (dmft/dmfs) index. The risk of bias in individual studies were assessed based on the National Institute of Health Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies. The GRADE system was used to perform quality assessment for each outcome reported.Results Following screening of 293 articles, a total of 32 studies qualified for qualitative review and 12 of them reported data that was used to conduct a meta-analysis. All included studies were cross-sectional in nature and presented a high risk of bias. Findings from meta-analysis showed that children who are overweight have a significantly higher dmft index (95% CI -0.64 to -0.14, P = 0.002, I2 equals 62 percent). The quality of evidence was found to be moderate.Conclusions Overweight and obese preschool children are at a greater risk of developing caries. Public health prevention programmes must target both conditions together to reduce their burden and effectiveness of prevention strategies.