Leveraging patient preferences can improve patient satisfaction and engagement in intentional health services. We explored desired health services preferences of marginalized populations accessing HIV-related care engagement to inform the implementation of an HIV prevention and treatment mobile clinic model. We conducted a maximum-difference survey with 154 people at community events and homeless encampments in Oakland, CA. Participants ranked 32 items in differentials of importance on a tablet, which were analyzed with Hierarchical Bayesian modeling. Fourteen services were prioritized, including housing, mental health counseling and screening, drug overdose prevention, personal hygiene, and food assistance. Participants indicated preferences for services that address basic physiological and safety needs (i.e., housing services, food, personal hygiene supplies, drug overdose treatment, and mental health support and engagement), physical examinations, screenings, and medication refills. Incorporating community-informed preferences into the development of services may improve engagement in care alongside a syndemic approach toward ending the HIV epidemic.