Platform leadership is a novel leadership mode that aims at fostering the mutual growth of knowledge-based teams. However, the specific mechanism of mutual growth among leaders, members, and teams remain unclear by scholars, especially how platform leadership, as the driving force of symbiotic systems, enables self-growth through his or her members. Drawing upon the social exchange theory and the process of downward learning, a serial mediation model is constructed in which platform leaders generate back-feeding from their team members through downward knowledge sharing, and lead to their job crafting to facilitate both individual growth and team routine renewal. Based on the data from two paired questionnaires with a total of 420 knowledge-based team leaders and 1,264 members, the study shows that platform leadership generates back-feed learning through downward knowledge sharing (Study 1), which triggers job crafting to achieve the leader’s own professional ability growth and team routine renewal (Study 2). This paper reveals a strategic mechanism by which platform leadership enables the mutual growth of knowledge-based teams, enhances the foundational understanding of platform leadership, and provides a scientific path for leaders to achieve both mutually beneficial team dynamics and self-management.