This systematic review and meta-analysis aimed to evaluate the association between Mediterranean diet (MedDiet)-based interventions and cardiometabolic biomarkers in children and adolescents. The study included nine randomized clinical trials (RCTs) involving 577 participants aged 3-18 years. The interventions were MedDiet-based and lasted a minimum of 8 weeks. The main outcomes were systolic blood pressure (SBP), diastolic blood pressure (DBP), triglycerides (TGs), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), glucose, insulin, and homeostatic model assessment for insulin resistance (HOMA-IR). The results showed that MedDiet-based interventions significantly reduced SBP (-4.75 mm Hg; 95% CI -8.97 to -0.52 mm Hg), TGs (-16.42 mg/dL; 95% CI -27.57 to -5.27 mg/dL), TC (-9.06 mg/dL; 95% CI -15.65 to -2.48 mg/dL), and LDL-C (-10.48 mg/dL; 95% CI -17.77 to -3.19 mg/dL). There was also a significant increase in HDL-C (2.24 mg/dL; 95% CI 0.34-4.14 mg/dL). However, no significant associations were found for DBP, glucose, insulin, or HOMA-IR. The quality of evidence for most biomarkers was moderate, except for SBP and serum glucose, which were graded as low quality. The HOMA-IR pooled estimate was of very low quality. Sensitivity analyses showed that the results were robust to the removal of individual studies. Publication bias was indicated by major asymmetry in the Doi plot and LFK index for certain biomarkers. The findings suggest that MedDiet-based interventions may be effective in optimizing cardiometabolic health in children and adolescents, particularly in reducing SBP, TGs, TC, and LDL-C, and increasing HDL-C. However, the limited number of RCTs and methodological limitations require further high-quality studies to confirm these findings.This systematic review and meta-analysis aimed to evaluate the association between Mediterranean diet (MedDiet)-based interventions and cardiometabolic biomarkers in children and adolescents. The study included nine randomized clinical trials (RCTs) involving 577 participants aged 3-18 years. The interventions were MedDiet-based and lasted a minimum of 8 weeks. The main outcomes were systolic blood pressure (SBP), diastolic blood pressure (DBP), triglycerides (TGs), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), glucose, insulin, and homeostatic model assessment for insulin resistance (HOMA-IR). The results showed that MedDiet-based interventions significantly reduced SBP (-4.75 mm Hg; 95% CI -8.97 to -0.52 mm Hg), TGs (-16.42 mg/dL; 95% CI -27.57 to -5.27 mg/dL), TC (-9.06 mg/dL; 95% CI -15.65 to -2.48 mg/dL), and LDL-C (-10.48 mg/dL; 95% CI -17.77 to -3.19 mg/dL). There was also a significant increase in HDL-C (2.24 mg/dL; 95% CI 0.34-4.14 mg/dL). However, no significant associations were found for DBP, glucose, insulin, or HOMA-IR. The quality of evidence for most biomarkers was moderate, except for SBP and serum glucose, which were graded as low quality. The HOMA-IR pooled estimate was of very low quality. Sensitivity analyses showed that the results were robust to the removal of individual studies. Publication bias was indicated by major asymmetry in the Doi plot and LFK index for certain biomarkers. The findings suggest that MedDiet-based interventions may be effective in optimizing cardiometabolic health in children and adolescents, particularly in reducing SBP, TGs, TC, and LDL-C, and increasing HDL-C. However, the limited number of RCTs and methodological limitations require further high-quality studies to confirm these findings.