<p>This study aims to investigate the cross-border buyer-supplier relational dynamics and suppliers’ dynamic capabilities for improving garment suppliers’ environmental sustainability and mitigating climate change vulnerabilities. Following a qualitative research approach and a multiple embedded case study method, data were collected from senior managers of two lead buyers and four garment suppliers in Bangladesh. Narratives were developed, and within and cross-case data analysis techniques were applied for data analysis. The study findings demonstrate that garment suppliers are highly affected by climate change and need to enhance dynamic capabilities to mitigate climate change vulnerabilities. Moreover, it shows that buyer-supplier collaboration is not optimal for improving garment suppliers’ environmental sustainability performance. This study also indicates that suppliers do not need to depend only on buyers’ assistance; instead, they must enhance their dynamic capabilities to mitigate climate change vulnerabilities and improve environmental sustainability.</p>