Background: Post-traumatic stress disorder (PTSD) and traumatic brain injury (TBI) have negative consequences on the health, rehabilitation, and quality of life for many United States (U.S.) military personnel. Digital technologies offer opportunities for the co-treatment of music therapy and occupational therapy to enhance the rehabilitation of injured service members. Objective: Case study to describe an interdisciplinary approach for comorbid symptoms of TBI and traumatic stress in an active duty service member. Both music therapy and occupational therapy approaches are highlighted. Methods: Case description Results: This intervention supported emotional state shifting from stress/anxiety to calm/regulated to stabilize their respiratory functioning and stress symptoms. Relaxation was further measured using heart rate variability (HRV) via biofeedback. Conclusions: Music technology played an essential role in the co-treatment space. Active music-making through traditional instrumentation and music listening to unaltered recorded songs did not comprehensively address the patient’s treatment goals. Combining a customized music listening tool, relaxation exercises, and HRV biofeedback demonstrated improvement in the service member’s physiological and psychological symptoms. Further investigation is needed to understand the impact of integrating digital music, health technologies, and a supportive co-treatment environment on rehabilitation success.