INTRODUCTION: People experiencing homelessness (PEH) have diverse and complex health and social needs and experience significant barriers to accessing support. As a result, PEH often use the emergency department (ED) for their unmet health and social needs. To address these challenges, the ED Outreach Programme at St. Michael's Hospital was developed with community partners within the Downtown East Toronto Ontario Health Team in Toronto, Canada. PEH presenting in the ED are connected to an outreach worker to identify immediate needs for a safe discharge and to access health and social supports in the community. Following discharge, the outreach worker continues to maintain contact with clients to ensure continuity of care and assists with the coordination, navigation and follow-up of healthcare and community services. METHODS: A three-phase community-based participatory research (CBPR) study will be conducted to evaluate patient experience in the ED Outreach Programme. Phase 1 involves conducting interviews with clients and staff/providers to understand their experiences with the programme and identify patient experience domains, constructs and measures. In Phase 2, programme clients, staff/providers and partners with lived experience co-design a set of patient-reported experience measures (PREMs) through focus groups. In Phase 3, the PREMs are pilot-tested to ensure their applicability and utility in the clinical setting. Central to CBPR principles, shared leadership and ownership of the project are facilitated by engaging and empowering community members. This study will contribute to new knowledge of building partnerships with PEH and marginalised communities in healthcare research, evaluation and quality improvement, particularly in developing PREMs. ETHICS AND DISSEMINATION: This study has been approved by the Unity Health Toronto Research Ethics Board (REB#21-315). Findings will be disseminated in peer-reviewed journals, conferences and forums, as well as through collaborating with partners with lived experience, community agencies and government bodies.