Rapid urbanisation in Global South cities has led to a progressive decline in accessible green and recreational spaces, resulting in increased environmental stress, lifestyle disorders, and deteriorating mental well-being. In metropolitan cities such as Chennai, rising temperatures, high-density development, and uneven distribution of public open spaces have intensified health vulnerabilities at the neighbourhood level. This study conceptualises urban green–recreational spaces as Urban Breathing Systems and examines their role as micro-scale health acupuncture interventions in promoting physical and mental well-being. Using Chennai City as a representative case of Global South urbanisation, the study adopts a mixed-methods and spatial analytical approach by integrating high-resolution satellite data, GIS-based accessibility measures, neighbourhood surveys, and secondary health records to construct composite indicators of green exposure, thermal comfort, recreational accessibility, and perceived well-being. Structural Equation Modelling (SEM) was employed to analyse the direct and indirect relationships between green–recreational infrastructure, environmental mediators, and health outcomes, supported by spatial regression and hotspot analyses to identify health-risk and green-deficit zones. The results reveal a statistically significant positive association between green recreational accessibility and both physical activity levels and psychological well-being, with thermal regulation and environmental comfort emerging as key mediating variables. Neighbourhoods with limited access to urban breathing systems exhibited higher stress levels and greater heat-related vulnerability. The study demonstrates that strategically distributed micro green–recreational interventions can function as effective urban health acupuncture in dense metropolitan contexts and provides an evidence-based framework for integrating health-sensitive green infrastructure into urban planning policies to support sustainable and resilient urban development in the Global South.