Individuals just released from prison, or returning citizens (RCs), face high mortality rates during the reentry period, with cardiovascular disease (CVD) being a leading cause. Peer mentors can support RCs' health, but they traditionally work in person, which may not always be feasible, particularly during pandemic outbreaks such as COVID-19. We used human-centered design to build a prototype of RCPeer, a web/mobile application (app) to support peer-led reentry efforts through CVD risk screening, action planning, linkage to resources addressing reintegration needs (e.g., housing, transportation), and goal-setting. We assessed feasibility, acceptability, and usability of RCPeer using mixed-methods. System Usability Scale (SUS) scores were 68 for peers and 66 for RCs, indicating good usability. Qualitative data suggests that RCPeer can support reentry tasks through RCs and peers sharing data, strengthen RC-peer relationships, and facilitate RCs meeting their goals. Future work is needed to enhance usability for RCs with limited technology experience.