<p>Cultural districts (CDs) provide places for leisure, recreation, and cultural exchanges, therefore, have the potential to enhance social cohesion. Urban development widely adopts cultural approaches, yet the role of CDs in urban health remains incompletely understood. This study contributes to this research by conducting a questionnaire survey and empirical analysis in Shanghai, China. Three key attributes of outdoor open spaces in CDs, namely cultural expressions, spatial design, and governance, are identified and validated in the study. A partial least squares structural equation model was developed to test the effects of CDs on mental health and the mediating role of social cohesion between CDs and mental health. Five constructs with 20 items validate the CDs-social cohesion-mental health model. The results indicate that CDs positively impact mental health, especially in reviving and revitalizing. In CDs, cultural expressions and spatial design have a moderate positive impact on mental health and a strong positive impact on social cohesion. Providing diverse cultural activities and integrating old and new architectural styles can enhance mental health and social cohesion in CDs. The study also identified that social cohesion has a strong positive impact on mental health and partially mediates CDs’ positive impacts on mental health. This study provides a reference for the governance and design of CDs that further enhance urban health, especially mental health.</p>