This study investigates how greenwashing narratives are constructed on short video platforms within Chinese-language and English-language contexts, focusing on cross-platform differences between Douyin and TikTok. A mixed-method approach was employed, combining quantitative content analysis of 147 high-engagement videos with qualitative framing analysis of selected call-to-action cases. Videos were analyzed based on creator type, industry context, framing functions, rhetorical and visual styles, and cultural orientation, with user engagement metrics used as outcome variables. The results show that TikTok content often features personal narratives and expressive tones, with critiques that target fast fashion brands and emphasize moral judgement. By contrast, Douyin videos are more likely to address systemic issues in ESG-related sectors, using neutral, informational framing and referring to regulatory actors. The study demonstrates how users across different platforms engage with greenwashing in culturally and contextually distinct ways, reflecting the interaction between narrative conventions, industry visibility, and platform-specific discourse environments. By integrating framing theory with cross-cultural analysis, the study offers an empirical lens on how sustainability discourse is reshaped by user participation in algorithmic media spaces.