Refereed/Peer-reviewed This research aims to examine consumers' green product purchasing intentions and observe how social media marketing (SMM) and social media usage (SMU) actively influence consumers' sustainable consumption behavior. We propose a new model for evaluating consumers' green purchase intentions (GPI) through social media (SM) by expanding the Theory of Planned Behavior (TPB) with additional variables, namely green thinking, social media usage, and social media marketing. 785 usable responses were collected using a self-administered questionnaire, and PLS-SEM was applied to perform the analysis. Findings suggest that attitude, subjective norms, perceived behavior control, green thinking, and social media marketing have a strong and positive association with the intention to purchase green products on social media. To the best of the authors' knowledge, this is the first empirical research to explore the moderating-mediating impact of social media usage interaction on the proposed TPB model, bridging research gaps by investigating the effect of consumers' green purchase intentions. Theoretical, managerial, and policy contributions are discussed.