Most of previous studies seek to understand buyer perspectives in green supply chain relationships and devote inadequate attention to the strategic role of upstream suppliers. Drawing on a market-oriented approach to sustainability, this paper examines the enabling factors and processes that underpin how export suppliers from emerging economies leverage their strategic intent to develop knowledge integration capacity for achieving improved export performance. The results from a sample of Chinese exporters show that the relational capacity of knowledge integration mediates the performance impact of market-oriented environmental sustainability, and such a mediating process of leaning is further enhanced by international buyer involvement. We reveal that relationship efforts should be directed at developing integrative capacity involving key partners for implementing proactive environmental strategy in international business-to-business (B2B) markets. This study contributes to the research of supply chain sustainability in a global context.