Purpose: Childhood and adolescent obesity is a major international public health crisis. It is crucial to prevent the negative effects of obesity at an early age by implementing appropriate lifestyle interventions, such as exercise training. We evaluated the effects of a combined resistance and aerobic exercise training (CET) regimen on arterial stiffness, vasoactive substances, inflammatory markers, metabolic profile, and body composition in obese adolescent girls. Methods: A total of 30 obese adolescent girls were randomly assigned to a CET (n = 15) or a control group (n = 15). The CET group trained for 3 days per week. Plasma nitric oxide, endothelin-1, C-reactive protein, arterial stiffness, glucose, insulin, the adiponectin/leptin ratio, and body fat were measured before and after 12 weeks. Results: There were significant increases (P < .05) in nitric oxide (4.0 μM) and adiponectin/leptin ratio (0.33); and decreases (P < .05) in arterial stiffness (−1.0 m/s), C-reactive protein (−0.5 mg/L), glucose (−1.2 mmol/L), insulin (−17.1 μU/mL), and body fat (−3.6%) following CET compared with control. There were no significant changes in endothelin-1 after CET or control. Conclusions: The findings of this study indicate that CET improves arterial stiffness, nitric oxide, and inflammatory and metabolic markers in obese adolescent girls. CET may have important health implications for the prevention of atherosclerosis at an early age.