Background <p>Care navigators are increasingly incorporated into medication for opioid use disorder (MOUD) treatment programs to address barriers to care and support patient engagement and retention. Prior research has largely focused on patient outcomes or program effectiveness, with limited attention to how frontline staff experience the integration of care navigators into routine treatment workflows. This study aimed to examine staff perceptions of care navigator roles and identify organizational and policy-relevant factors influencing their implementation.</p> Methods <p>We conducted a qualitative study of staff perceptions of care navigators embedded in medication for opioid use disorder treatment centers participating in the HEALing Communities Study in Kentucky, USA. Semi-structured interviews were conducted with clinical and administrative staff working in participating treatment centers. Interviews explored experiences with care navigator integration, perceived impacts on patient engagement and team functioning, and implementation challenges. Data were analyzed using thematic analysis guided by the Reach, Effectiveness, Adoption, Implementation, and Maintenance framework and the Practical, Robust Implementation and Sustainability Model.</p> Results <p>Staff described care navigators as filling critical service gaps by helping patients address practical challenges that commonly disrupt treatment engagement, including transportation barriers, housing instability, and navigating health and social services. These efforts were viewed as supporting sustained engagement in treatment with medication for opioid use disorder. Participants also reported improved team morale and reduced burnout following care navigator integration. However, staff identified persistent implementation challenges, including unclear role boundaries, scheduling constraints, and misalignment between organizational cultures. Clear differentiation between care navigators, targeted case managers, and peer support specialists was consistently identified as necessary to support effective collaboration.</p> Conclusions <p>Findings suggest that care navigators may enhance engagement and workforce capacity in medication for opioid use disorder treatment settings, particularly when focused on addressing practical barriers to care. At the same time, variability in role definition and organizational fit limited effectiveness in some settings. These results highlight the importance of clear role delineation, stable funding, and implementation planning when integrating non-clinical navigation roles. Future research should incorporate patient perspectives and examine how policy and organizational contexts shape implementation and outcomes.</p> Trial registration <p><a href="https://ClinicalTrials.gov">ClinicalTrials.gov</a> Identifier: NCT04111939 (registered March 26, 2019).</p>