This systematic review and meta-analysis investigated the association of polycystic ovary syndrome (PCOS) with the metabolic syndrome (MetS) in adolescent girls aged 10–20 years. It included 13 observational studies with a total of 1,789 participants (1,005 with PCOS and 784 controls). Adolescent women with PCOS had a significantly higher risk of MetS than controls (OR: 2.61, 95% CI: 1.83–3.74, p < 0.001). The PCOS group showed higher values of waist circumference (WMD: 3.23 cm, 95% CI: 0.91–5.55, p = 0.006), systolic blood pressure (WMD: 3.80 mmHg, 95% CI: 0.59–7.01) and triglyceride levels (WMD: 5.76 mg/dL, 95% CI: 1.05–10.46, p = 0.017). No significant differences were found in diastolic blood pressure, high-density lipoprotein, or fasting glucose levels. The study recommends routine screening for these three components of MetS in adolescents with PCOS and lifestyle interventions to prevent complications.