In an era of global sustainability challenges, design education faces inherent limitations when confined to monocultural contexts. While cross-cultural communication holds promise for transcending these limitations, its specific mechanisms for fostering conceptual innovation in sustainable design education remain underexplored. This study investigates how cross-cultural collaboration influences conceptual generation in sustainable design education. To operationalize this inquiry, a three-stage “Orientation-Practice-Assessment” pedagogical framework was developed and validated for short-term cross-cultural projects. A comparative design was employed, involving an experimental group of 44 students from 15 countries across Asia, Europe, Africa, and Oceania, and a control group of 34 monocultural Chinese students. Guided by constructivist epistemology, data were collected through semi-structured interviews, participatory observations, and design outcome analyses, and analyzed using Gioia methodology and triangulation. Findings reveal that cross-cultural groups activated tacit knowledge through cognitive conflicts and value negotiations, shifting design thinking from technical execution to value deliberation. This shift represents a paradigm move from problem-solving to social diagnosis. In contrast, monocultural groups remained within established conceptual frameworks, applying explicit knowledge to technical optimization. This study demonstrates cross-cultural communication as a catalyst for transforming sustainable design education from skills training toward ethical internalization and paradigm innovation, offering new epistemological insights for integrating global and local perspectives in design education.