Context Inclusion of people who use mental health services in policymaking is a goal of many mental health systems. However, the outcomes of such involvement have not been well articulated or researched. Objectives The objectives of this research were to explore how the social and personal outcomes of citizen‐user involvement in mental health policymaking were conceptualized by policy actors and to create a conceptual framework to guide the development and evaluation of citizen‐user involvement. Design This qualitative instrumental case study explored the phenomenon of citizen‐user involvement using the policy field of mental health and social housing policy in the Province of Manitoba, Canada, as the focal case. Participants A total of 21 informants from four policy actor groups, citizen‐users, representatives of advocacy organizations, government officials and service providers, participated in key informant interviews. Data also included policy documents relevant to the policy field. Analysis Data collected from interviews and policy documents were analysed using an inductive qualitative paradigm. Results Participants identified multiple outcomes of citizen‐user involvement in policymaking. The resulting conceptual framework illustrated how outcomes in personal, substantive, instrumental and normative dimensions influence micro‐, meso‐ and macrosocial structures. The results also provided a cautionary tale by suggesting how attention needs to be paid to managing the risks as well as optimizing the rewards of involvement. Conclusions The framework has application in guiding the development and evaluation of mechanisms that aim to involve citizen‐users in policymaking. The framework encourages an approach that takes into account the complexity and multidimensional nature of engaging citizen‐users.