The correlation between depressive and cognitive symptoms and OSAS (obstructive sleep apnea syndrome) is between 5 and 63%. We reported the case of two patients with severe OSAS and its associated depressive symptoms that were intolerant to continuous positive airway pressure (C-PAP) and underwent maxillomandibular advancement (MMA) surgery. The severity of cognitive and depressive symptoms was assessed using validated questionnaires (Beck Depression Inventory, Beck Anxiety Inventory, Epworth Sleepiness Scale, and quality of life), medical observation, and patient-reported symptoms. We performed pre- and post-treatment polysomnography. Six months after treatment, the value of the apnea–hypopnea index (AHI) had returned to the normal range and, together with it, the depressive component was considerably reduced and the patients’ overall quality of life (BDI, BAI, ESS, and qol) improved. Conclusion: We described significant improvement in all the analyzed parameters, such as physical and mental functioning, and depression and anxiety rates.