OBJECTIVES: Individuals with co-occurring opioid use disorder (OUD) and mental health disorders experience complex treatment trajectories. The collaborative care model (CoCM) is an effective approach for improving behavioral health outcomes in primary care, but has not been tested for patients with co-occurring disorders. We sought to understand patients' experiences receiving CoCM for co-occurring OUD and depression and/or PTSD. METHODS: We conducted interviews with patients (N=24) who received CoCM for co-occurring disorders as part of a randomized trial. CoCM was delivered across 18 clinics by 10 care managers who were community health workers embedded into primary care teams. Themes were identified by 2 coders using rapid content analyses. RESULTS: We identified 4 major themes. First, patients hoped CoCM would provide an opportunity to make OUD treatment possible by helping them navigate barriers. Second, patients thought that OUD and mental health disorders were connected and that treatment should be integrated. Third, patients felt that care managers improved their treatment, emphasizing how their compassionate style and commitment facilitated access to and retention in medications for OUD and mental health disorders. Finally, patients reported experiencing barriers to accessing mental health therapy, although support from care managers sometimes helped address those barriers. CONCLUSIONS: Patients expressed how care managers facilitated their positive experience with treatment and decreased access barriers common for individuals with co-occurring conditions. Our findings inform how community health workers in the role of care managers can facilitate access to and retention in care for people with co-occurring disorders.