Objective: To compare peripheral muscle oxygenation levels and the prevalence of psychological stress in adolescents with and without temporomandibular disorder (TMD). Methods: A cross-sectional study was performed with adolescents submitted into two groups: those diagnosed with TMD (DG) and control (CG). Muscle oxygenation was measured by near-infrared spectroscopy in the masseter and upper trapezius muscles. Symptoms of stress were assessed by Lipp’s Stress Symptom Inventory for Adults or Child Stress Scale. A Student t-test was used for intergroup comparisons and association between categorical variables by chi-square test, phi coefficient of correlation, odds ratio, and two-way ANOVA. Results: Fifty-three adolescents were evaluated and a significant reduction was observed in the oxyhemoglobin level in the masseter muscle at rest (p = 0.04) and contraction (p = 0.02). A greater total hemoglobin level was found in the upper trapezius muscle at rest in DG (p = 0.03), with a significant difference in the tissue saturation index during contraction (p = 0.05) intergroup. Individuals in the DG were 4.523 times more likely to exhibit signs and symptoms of stress than in CG. Conclusion: Adolescents from DG showed reduced masseter oxyhemoglobin values at rest and during contraction and showed more signs and symptoms of stress than healthy controls. In the upper trapezius, DG showed higher values of total circulating hemoglobin, essential for greater blood flow and efficient maximum voluntary contraction. Clinical relevance: Changes in tissue oxygenation and stress in adolescents with TMD prompted the earlier treatment of this population to prevent disease progression into adulthood. Keywords: Muscle oxygenation; Near-infrared; Psychological stress; Spectroscopy; Teenagers; Temporomandibular joint disorder(s).