<p>In the context of urbanization and an aging society, understanding how urban environments can sustainably support well-being for older people is important. Urban green spaces can provide cultural ecosystem services as an interaction to facilitate the transformation of social capital into social cohesion, thereby enhancing their well-being. This study aims to evaluate the relationships between cultural ecosystem services and social cohesion by using visible landscape design elements as indicators of cultural ecosystem services. A face-to-face questionnaire survey was conducted by interviewing 625 older adults across five urban green spaces, urban community parks, in Chengdu, China. Ordinal Logistic Regression was employed to analyze the relationships between cultural ecosystem services and social cohesion. Findings indicate that social interaction is identified as a key interaction strengthening social cohesion and different constituents responding selectively to cultural ecosystem services. Namely, landscape design elements of activity spaces, trails, water bodies, and hills, statistically significantly improved social cohesion, and in each community park, activity spaces and trails consistently had statistically significant positive effects, while vegetation had a statistically significant negative effect. Building on the empirical results, we propose maturity as a conceptual refinement for interpreting social cohesion and suggest an empirical extension through urban planning, thereby providing a framework for future research. These insights inform Chengdu’s Park City Policy, Age-Friendly Cities and Communities, and the target 11.7 of Sustainable Development Goal 11 by demonstrating how inclusive UGSs foster socially sustainable cities for older people. </p>