<p>Rapid urbanization has resulted in eco-environmental degradation, leading to the global implementation of green infrastructure strategies, such as the Green Heart, to balance urban development with nature conservation. The Changsha-Zhuzhou-Xiangtan Green Heart in China represents an important example of addressing eco-environmental issues within urban agglomerations. However, current research lacks empirical assessments of its multifunctional effectiveness. This research develops a multidimensional framework that integrates 14 eco-environmental and socio-economic indicators spanning the years 2014 to 2022 to address this gap. Employing the CRITIC-entropy weighting and coupling-coordination degree model, the findings indicate that, despite a substantial increase in socio-economic effectiveness driven by growth in tourism-related infrastructure and economic output, eco-environmental effectiveness remained limited, as evidenced by a marked decline in water conservation volume and ecological corridor connectivity. The coupling-coordination degree improved from slightly uncoordinated to slightly coordinated, showing gradual but incomplete harmony in socio-economic development and eco-environmental conservation. The Changsha-Zhuzhou-Xiangtan Green Heart planning presents potential for advancing a green development model; however, its eco-environmental challenges impede the realization of key eco-environmental objectives, thereby questioning its viability as a sustainability model and similar risks for other projects in rapidly urbanizing regions. This study offers a replicable framework for evaluating Green Heart planning and governance, delivering practical insights for sustainable urban planning in China and contributing to global discourse on green infrastructure in rapidly urbanizing areas.</p>