Abstract Background and Objectives The construction of an Age-friendly City (AFC) requires active contribution from relevant interest groups including older adults, non-profit organizations, and policymakers. However, given that relevant interest groups may have limited resources, knowledge, and skills, as well as unique contextual factors, they often require help from intermediary organizations – actors that aim to build interest groups’ capabilities. Our objectives were to examine the functions of universities, as an example of intermediary organizations, in facilitating the construction of an AFC, and identify critical factors that enable intermediary organizations to perform their functions. Research Design and Methods We conducted three focus groups and one individual interview with multiple interest groups including older adults and social workers from non-profit organizations and local government involved in a six-year citywide Age-friendly City project in Hong Kong. Participants were asked to share their views on the role of universities in relation to their own experiences and roles in the project. Data generated from the interviews were analyzed using thematic analysis. Results Four themes pertinent to the functions of universities in facilitating development were identified: facilitating cross-sector collaborations, knowledge diffusion, interest group-building, and mediating divergent interests. We also found that neutrality and reputability are key characteristics for intermediary organizations to wield sufficient legitimacy to perform their functions efficiently. Discussion and Implications Findings underscore the important yet overlooked role of intermediary organizations in bridging and mediating different interest groups to facilitate AFC development. We advance gerontological scholarship by providing insights into the theoretical mechanisms and practice implications for intermediary organizations in fostering an Age-friendly City.