This paper aims to explore the effect of humble leadership on project management effectiveness by integrating the mediating role of employee creativity. Top management support moderates the direct (humble leadership and project management effectiveness) and indirect relationships through employee creativity. Time-lagged data were obtained from 332 persons working in a matrix organization on sustainable information technology projects. The results show that humble leadership enhances project management effectiveness by mediating and moderating processes. This study provides a solution to an underlying research question that has gone unanswered in prior studies. What are the strategies proposed for humble leadership in fostering the effectiveness of project management?