Background <p>The prevalence of acquired brain injury (ABI) and mental health/substance use (MHSU) disorders is high amongst people experiencing homelessness, yet guidance for addressing these complex comorbidities is lacking. Therefore, the objective of this study was to engage community-based stakeholders in a health priority-setting process to generate, identify and prioritize recommendations for clinical practice and research to improve healthcare services for individuals with concurrent ABI-MHSU who are experiencing homelessness.</p> Methods <p>Data were collected during a one-day workshop as part of the BC Consensus on Brain Injury. Participants were 163 stakeholders in the ABI-MHSU and homeless communities (<i>M</i>_<i>age</i> = 46.40, <i>SD</i> = ± 13.80, 72% female), including service providers, people with lived experience, healthcare professionals and other community-based stakeholders. Stakeholders participated in concurrent focus groups based on the nominal group technique. Initial recommendations were generated then collated, themed and rank-ordered by priority and a consensus voting method was used to identify the top five priorities for research and clinical practice.</p> Results <p>Stakeholders discussions and subsequent prioritization evaluations identified the following recommendations for clinical practice: (1) Provide accessible and affordable supportive housing; (2) enhance resources (financial, human) for healthcare service providers; (3) design needs-based services that promote quality of life; (4a) improve communication and collaboration between service providers; (4b) adopt a long-term and integrated approach; and (5) reduce stigma and discrimination through public health education. Recommendations for research, also ordered by priority, included: (1) Evaluate and optimize existing interventions for immediate implementation; (2) develop specialized interventions and diagnostic techniques; (3) collect meaningful data to better understand impacts and intersections; (4) increase mechanisms for knowledge transfer; and (5) explore methods for risk identification and prevention.</p> Conclusions <p>This is the first study to identify and prioritize recommendations for research and clinical practice related to healthcare services for people experiencing homelessness with concurrent ABI-MHSU conditions. The stakeholder-generated recommendations from this study provide a valuable resource for researchers, clinicians and policymakers to enhance care for this underserved population.</p>