Wrist circumference is a clinical marker for insulin-resistance in overweight/obese children and adolescents. Insulin resistance is considered a major determinant of increased vascular resistance and hypertension. The aim of the study was to investigate the association between wrist circumference and systolic (S) and diastolic (D) blood pressure (BP) in a population of overweight/obese children and adolescents. A population of 1133 overweight/obese children and adolescents (n = 1133) were consecutively enrolled. Multivariate regression analyses were used to investigate the influence of independent variables on the variance of BP. The prevalence of hypertension was 21.74% in males and 28.95% in females (p = 0.048). The results showed that SBP was significantly associated with wrist circumference in both genders (p < 0.0001 for both comparisons). We found no association between DBP and wrist circumference in either gender. Wrist circumference accounted for 17% of the total variance of SBP in males and 14% in females. Wrist circumference, a marker of insulin resistance, is associated with increased SBP in overweight/obese children and adolescents, suggesting a role of insulin resistance in the pathogenesis and development of hypertension.