One third of US military veterans suffer from some type of psychological distress. Cognitive behavioral therapy (CBT) has emerged as the standard practice for reducing psychiatric symptoms but suffers from high dropout rates (25–40%) and low compliance. Emerging mobile applications can augment CBT and improve the mental health outcomes of both Service members as well as the general public. In the current paper, we discuss the development and evaluation of a mobile health (mHealth) system for stress and anger management, which consists of a mobile application and wrist-worn sensor band (smartwatch) for end users as well as a web-based portal for mental health providers. The mobile app detects stress objectively and in real time via a unique, AI-based classifier of stress that leverages data collected from the smartwatch and alerts end users when high levels of stress are detected. Users can then self-report contextual information about their stress events within the app, such as triggers and location. The app also includes tools to reinforce stress reduction techniques learned during CBT, including heart rate variability (HRV) biofeedback, deep breathing, progressive muscle relaxation, and guided meditation exercises. Mental health providers can use the system to access stress/sleep data and analytics via a HIPAA-compliant, web-based portal. This information helps providers to track users’ progress and improve therapy sessions. Use of this system in a group of military Veterans (n = 16) in conjunction with CBT resulted in significant improvements on outcome measures of stress, anxiety, and anger as compared to standard CBT. Veterans using the system were also significantly less likely to discontinue therapy. An ongoing, follow-up trial with active duty Service members (n = 30) intends to replicate these results. Preliminary findings from that trial are discussed here, along with avenues for future work involving the mHealth system.