As environmental issues intensify, sustainability development is becoming mainstream, with environmental topics gaining increasing attention in the media and online. Shifting consumer behavior in China toward green purchasing is crucial for mitigating environmental pollution and achieving sustainable, low-carbon consumption. This study constructed a theoretical model combining media persuasion (MP) and positive internet word-of-mouth (PIM) with green purchasing behavior (GPB), based on the Stimulus–Organism–Response (SOR) and persuasion theories, to explore consumer responses to environmental information campaigns. A total of 357 valid samples were collected through an online questionnaire survey and subjected to analysis using the structural equation model (SEM). The results indicate that MP, PIM, and environmental attitude (EA) significantly influence GPB. Specifically, EA partially mediates the relationship between MP, PIM, and GPB, while environmental knowledge (EK) negatively moderates the relationship between independent variables and EA. Additionally, EK moderates the mediating effect of EA. The findings highlight that the effective implementation of MPs and PIMs can facilitate the creation of positive EA, which stimulates consumer GPB. This is essential for promoting sustainable consumption. This research contributes to sustainability by providing insights and practical suggestions for developing green marketing strategies that support environmental goals.