<p>Against the backdrop of continuously deepening population aging, the physical and mental health of older adults has become a significant research topic in academic circles. However, existing studies have not yet established a clear understanding of the mechanisms linking living environments to the physical and mental health of older adults, and a notable gap remains regarding gender-specific variations in these associations. Based on the social ecology theoretical framework, this study uses 9998 valid samples from the China Longitudinal Aging Social Survey (CLASS 2023) to construct a theoretical analysis model of “living environment—social adaptation—physical and mental health,” and systematically explores the complex relationships among living environments, social adaptation, and the physical and mental health of older adults through structural equation modeling. The findings reveal that living environment is significantly positively correlated with the physical and mental health of older adults, with a notably stronger correlation to mental health than to physical health. Social adaptation plays a partial mediating role in the process through which the built environment affects physical and mental health. Gender difference analysis reveals that the correlation between the living environment and the physical and mental health as well as social adaptation is more pronounced among male older adults.The research conclusions provide empirical evidence for differentiated aging-friendly environmental planning, and it is recommended that gender-differentiated environmental intervention strategies be established in urban planning practices to promote the overall health of older adults.</p>