Abstract: Green spaces are increasingly recognized as playing a crucial role in enhancing human well-being. Currently, people’s demand has gradually shifted from residential green spaces, which is emphasized by neoliberalism for enhancing quality of life, to the emotional benefits provided by outside-residential green spaces after post-COVID-19. However, knowledge about how different types of green spaces promote various dimensions of subjective well-being is still limited, hindering the understanding of green spaces-well-being benefits and effective implementation of spatial planning. In this paper, we combines nature connectedness with supported activities to construct a multiple mediation model. Based on a cross-sectional survey of 909 urban residents in Nanjing, China from October to November 2023, the study aims to explore the differentiated effects of two major types of green spaces—outside-residential green spaces and residential green spaces—on the affect and life satisfaction components of subjective well-being. We found that outside-residential green spaces were more effective in promoting affect, while residential green spacess were more effective in promoting life satisfaction. Outside-residential green spaces highlighted the importance of nature connectedness, whereas residential green spacess emphasized the diversity of supported activities. This study further reveals the significance of engagement in green spaces and pronounced spatial differentiation in green spaces–subjective well-being effects. We urged policymakers to comprehensively consider the well-being benefits of green spaces, especially through spatial planning to optimize the distribution and investment of green spaces.