This study explores the critical role of interrelationships among e-commerce supply chain members in shaping sustainability outcomes. It adopts a qualitative approach, drawing from Sustainable Supply Chain Management (SSCM) and Resource Dependency Theory (RDT) to gain a deeper understanding of sustainability within e-commerce supply chains. In a comprehensive investigation involving 35 key stakeholders from prominent e-commerce companies in China, such as Amazon, Alibaba, Suning.com, Shein, and Wayfair, this research examines how robust interrelationships, characterized by collaboration, knowledge exchange, trust-building, and joint problem-solving, facilitate efficient resource utilization, innovation, waste reduction, and enhanced social and environmental responsibility throughout the supply chain. The findings underline the practical implications for supply chain managers and practitioners, emphasizing the need to foster these robust interrelationships through effective communication, trust-building, collaboration, and information sharing as tangible strategies to elevate sustainability performance and gain a competitive edge in the dynamic e-commerce landscape. The insights are based on structured, in-depth interviews conducted in English with participants familiar with the language, lasting approximately 35 to 55 min.