International collaboration for sustainable development is increasingly crucial in the face of global environmental challenges. This article presents a conceptual framework and relevant approaches for such collaboration, focusing on the Third Space—a dynamic arena where diverse cultures converge, contest, and cooperate. Drawing on a China-US sponge city exchange as a case study, the article explores how language and communication, relationships and culture, team performance and policies, and technology and outreach intersect in the pursuit of sustainable urban development. Through autoethnographic analysis grounded in pedagogical theories and real-world experiences, the study elucidates key themes and strategies for successful international collaboration, answering the question “how can international teams better collaborate towards sustainable development?” The resulting conceptual framework provides valuable insights for practitioners, policymakers, and researchers seeking to navigate the complexities of sustainable development across international borders.