<p>Deep interaction is pivotal for fostering higher-order knowledge construction in online collaborative learning. Yet, current practice often suffers from shallow exchanges and inefficient collaboration, which severely constrains advances in collaborative knowledge building. To address this challenge, this study conducted three iterative design cycles to develop and refine a teacher–student interaction framework comprising three phases: individual knowledge construction, teacher-guided argumentation, and learning-community-based co-creation. Adopting a design-based research approach, this study examined the framework’s effectiveness through three rounds of iterative teaching experiments. Using a mixed-methods design that integrated social network analysis and content analysis, this study focused on the implementation effects of several support strategies, including a four-component topic design, selective teacher interventions, a role-playing mechanism, and a What, Why, Where, Which, Who (5W) reply model. The results suggest that the implementation of the framework was associated with increased social interaction density, improved quality of discussion posts, and a progression in collaborative knowledge building from simple information sharing toward negotiated consensus and co-creation. The teacher’s role evolved dynamically from peripheral participant to central leader and then to a supportive node, thereby illuminating principles for the adaptive enactment of teaching presence in collaborative learning. This study offers contextually grounded design principles and a detailed practice case that may inform the design and optimization of teacher–student interactions in similar online collaborative learning environments.</p>