Since many people now live with human immunodeficiency virus (HIV) as a complex, chronic health condition that may require frequent medical and psychosocial services, a potential new role for HIV-positive peers involves support during an inpatient admission that extends past discharge to improve the transition home from hospital. We sought to begin outlining scope of peer support in complex HIV care, by detailing a training curriculum alongside experiences and recommendations by Peer Volunteers. A community-clinical partnership designed a personalized peer intervention for people living with HIV who were acutely hospitalized and struggling with antiretroviral adherence and substance use. Five Peer Volunteers delivered the program, which involved being matched with a participant for a pre-discharge in-person meeting followed by frequent phone contact in the 7 weeks following discharge. A 4-day peer training focused on active listening, structuring a call, use of self, boundaries, and facilitating program closure. The curriculum was informed by theories of change, motivational interviewing, and simulation. Peer Volunteers participated in pre-match and post-match interviews with peer researchers (also living with HIV). Thematic analysis was employed by four independent coders to understand how prepared peers were and areas for program improvement. Peers verified participant feelings and affirmed their experiences, followed-up on participant goals to track progress, disclosed their own relevant experiences to build rapport, and facilitated closure to enable program success. Peers struggled maintaining an emotional connection over the phone and were concerned when participants were nonresponsive. This article discusses how the training was piloted and adapted for practice.