The rapid expansion of e-commerce in Indonesia has created new opportunities and challenges for promoting environmentally friendly consumption. This study investigates the intention–behavior gap in green purchasing on e-commerce platforms by focusing on three key constructs: perceived convenience, trust-based online shopping expectations, and green purchase intention/behavior. Data from an online survey of 174 active e-commerce users, selected via purposive sampling, were analyzed using descriptive statistics, correlation analysis, and partial least squares structural equation modeling (PLS-SEM). The measurement model demonstrates satisfactory reliability and convergent validity for all three constructs. The results show that perceived convenience significantly enhances trust-based expectations and green purchase intentions, while trust-based expectations strongly predict intention. Green purchase intention is very closely associated with actual green purchasing behavior, yet a small but meaningful intention–behavior gap persists at the aggregate level. The study also identifies a dual gap: an objective discrepancy between intention and behavior, and a subjective tendency among consumers to underestimate this inconsistency, indicating optimism bias. Theoretically, the findings confirm an integrated TPB–TAM–UTAUT model in the context of green e-commerce, highlighting the mediating roles of convenience and trust-based expectations. Practically, the results emphasize the importance of aligning online shopping experiences with perceived convenience and trust to effectively convert strong pro-environmental intentions into consistent green purchasing behavior in Indonesia’s expanding e-commerce market.Keywords: Intention–behavior gap; perceived convenience; online shopping expectation; trust-based expectation; green purchase intention; green purchasing behavior; e-commerce Indonesia