Black patients and those with co-occurring mental health disorders are disproportionately affected by chronic pain, but few interventions target these populations. This is a secondary analysis of a randomized trial of a walking-focused proactive counseling intervention for Black Veterans with chronic musculoskeletal pain (ACTION). The primary aim was to examine intervention effectiveness among Veterans with an electronic health record-documented mental health diagnosis [depressive disorder, anxiety disorder, substance use disorder, post-traumatic stress disorder or serious mental illness (n = 205)] and those without a diagnosis (n = 175). About 380 Black Veterans receiving care at the Atlanta VA Health Care System were enrolled from 2016 to 2019 and randomized to the intervention or usual care (UC) (1:1). The intervention featured 6 telephone coaching sessions over 8-14 weeks to encourage walking. Participants with a mental health disorder were more likely to complete all counseling sessions (56% vs 38%) and reported improvements in global perceptions of pain and pain intensity/interference (secondary outcomes) at 3-months vs UC. Among participants without a mental health disorder, the intervention was associated with an improvement in pain-related disability at 6-months (primary outcome). Black chronic pain patients with co-occurring mental health disorders may require more intensive treatment to affect improvement in pain-related disability. PERSPECTIVE: This study examines the effectiveness of a walking intervention for chronic pain among Black Veterans with a mental health disorder. These patients were more engaged with the intervention than those without a mental health disorder. However, they did not experience reductions in pain-related disability, suggesting more intensive treatment is needed.