Improving access to evidence-based psychotherapies (EBPs) is a Veterans Health Administration (VHA) priority. Cognitive behavioral therapy (CBT), acceptance and commitment therapy (ACT), and mindfulness-based stress reduction (MBSR) are effective for chronic pain and several mental health conditions. We synthesized evidence on implementation strategies to increase EBP access and use. We searched MEDLINE, Embase, PsycINFO, and CINAHL from inception until March 2021 for articles on EBP implementation within integrated health systems to treat chronic pain or chronic mental health conditions. Reviewers independently screened articles, extracted results, coded qualitative findings, and rated quality using modified criteria from Newcastle-Ottawa (quantitative results) or Critical Appraisal Skills Programme (qualitative results). We categorized implementation strategies using the Expert Recommendations for Implementing Change (ERIC) framework and classified outcomes using RE-AIM domains (Reach, Effectiveness, Adoption, Implementation, Maintenance). Twelve articles (reporting results from 10 studies) evaluated CBT (k = 11) and ACT (k = 1) implementation strategies in large integrated healthcare systems. No studies evaluated MBSR implementation. Eight articles evaluated strategies within VHA. Six articles reported on national VHA EBP implementation programs; all involved training/education, facilitation, and audit/feedback. CBT and ACT implementation demonstrated moderate to large improvements in patient symptoms and quality of life. Trainings increased mental health provider self-efficacy in delivering EBPs, improved provider EBP perceptions, and increased provider EBP use during programs, but had unclear impacts on Reach. It was unclear whether external facilitation added benefit. Provider EBP maintenance was modest; barriers included competing professional time demands and patient barriers. Multi-faceted CBT and ACT implementation programs increased provider EBP Adoption but had unclear impacts on Reach. Future implementation efforts should further evaluate Reach, Adoption, and Maintenance; assess the added value of external facilitation; and consider strategies targeting patient barriers. Future work should use implementation frameworks to guide evaluations of barriers and facilitators, processes of change, and outcomes. PROSPERO registration number CRD42021252038. © 2023. This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply.