The presence of people living on the streets is a global social drama. Homeless living conditions negatively impact mental health leading to poor longevity, fragility of social bonds, violence, prejudice, discrimination, lack of privacy, lack of education, and infrastructure for self-care. On the other hand, the presence of mental disorders keeps people homeless. Addressing the intersection of homelessness and mental health demands a culturally sensitive approach that acknowledges the diversity of experiences and cultural backgrounds. Collaboration with local communities can pave the way for more inclusive policy-making practices, ultimately leading to more effective and culturally relevant interventions for homeless populations both in Brazil and globally. By actively involving community members, service providers, and researchers in the research process, community-based participatory research (CBPR) ensures that policy interventions are grounded in the lived experiences and cultural contexts of the homeless population. This chapter explores CBPR’s role in addressing cross-sectoral issues of homelessness and mental health and highlights the importance of community involvement in policy development processes through a collaborative approach to inclusive and culturally sensitive policy making. Furthermore, by exploring innovative Brazilian health system initiatives, the chapter addresses issues such as power dynamics, cultural humility, and sustainability, offering recommendations for overcoming these challenges and promoting inclusive policy-making practices.