Hypovitaminosis D and increased cardiometabolic risk have been well established in adults. This study aims to determine whether or not vitamin D also influences cardiometabolic risk in children and adolescents. To test this hypothesis, we recruited 186 boys (mean age 12.4 ± 3.7 years) and 114 girls (11.6 ± 3.7) in a cross-sectional observational study. Anthropometrics were obtained and morning fasting blood samples were collected. Serum glucose and lipid profile were determined using routine methods. Serum 25-hydroxyvitamin D was quantified using an enzyme-linked immunosorbent assay. In our population, approximately 10% of subjects had severe 25-hydroxyvitamin D deficiency (< 12.5 nmol/L), while 50% of the boys and 40% of the girls had mild vitamin D deficiency (12.5–24.9 nmol/L). Circulating 25-hydroxyvitamin D concentrations were inversely correlated with age, body mass index (BMI), blood pressure, waist and hip circumferences and serum triglyceride concentrations, and positively associated with HDL-cholesterol. Age and systolic blood pressure were significant predictors of 25-hydroxyvitamin D, explaining about 30% of the variance (p = 0.0005). In conclusion, significant associations between serum 25-hydroxyvitamin D and cardiometabolic parameters support promising cardioprotective benefits from vitamin D sufficiency at an early age. Follow-up with prospective clinical intervention studies are needed to validate this hypothesis.