Interprofessional learning (IPL), which is learning arising from the interaction between representatives of two or more professions, has not been studied extensively in relation to peer support workers (PSWs) in mental health care teams. PSWs support others who face challenges with their own experience of similar challenges of mental health problems. The role of PSWs has been studied in mental health care interprofessional teams. However, researchers have not paid attention to IPL where the PSWs contribute their knowledge. This paper is a scoping review that aims to highlight existing knowledge of the PSW role and expertise in IPL in the context of mental health care. The findings show knowledge of (a) the key factors and challenges when interprofessional teams include the PSW role, (b) the legitimacy of the PSWs' role and expertise, and (c) the benefits of the PSW role. A knowledge gap was identified of teams' use of PSWs' expertise and its implications for IPL.