Encouraging low-carbon behavior and adopting sustainable green lifestyles are crucial to safeguarding the ecological environment. To promote the sustainable development of humans, society, and the environment, it is essential to establish a harmonious relationship between residents’ well-being and the environment. This study investigates the differences of associations in residents’ subjective well-being and multiple types of low-carbon behaviors with place attachment as a mediator using a structural equation model based on a questionnaire survey of the residents of Hangzhou, China. The findings reveal that subjective well-being has a positive and significant effect on place attachment, and place attachment has a positive and significant impact on multiple types of low-carbon behaviors. Furthermore, the mediating effect test shows that place attachment plays a partial mediation role in the influence path of subjective well-being on habitual low-carbon behavior. In contrast, it plays a full mediating role in the influence path of low-carbon purchasing and travel behavior. Based on the emotion-behavior theory, this paper highlights the positive role of subjective well-being in promoting positive human-environment interaction by focusing on microscopic individual behavior. It provides policy implications for the government to promote the adoption of residents’ low-carbon behaviors.