Approximately 30%-50% of people with schizophrenia worldwide have treatment-resistant schizophrenia (TRS). Currently available standard psychopharmacological and psychological treatments have proven insufficient to achieve full recovery in these patients. Alternative psychological interventions focused on improving emotion regulation, such as the Unified Protocol for Transdiagnostic Treatment of Emotional Disorders (UP), could potentially improve treatment outcomes in this difficult to treat population. The aim of the present case study is to demonstrate how the UP can be adapted for the treatment of TRS. We decided to use UP to treat this particular patient due to the presence of intense unpleasant emotions, aversive reactions, and emotional avoidance strategies. After completing the full treatment protocol, the patient showed significant decreases in scores on the Difficulties in Emotion Regulation Scale (DERS), including total and emotional rejection, life interference, and emotional lack of control. A significant reduction was also observed in anxiety (OASIS) and depressive symptoms (ODSIS). The intervention had a positive impact on auditory hallucinations, with decreased severity, less intense anxiety, and less interference in life. The treatment led to greater control over voices and the patient reported feeling more confident in her relationship with those voices. These results provide preliminary support for the use of UP for the treatment of TRS.