Adopting knowledge management theories from an inter-organizational perspective, this study aims to uncover the relationships among information sharing (IS), knowledge organization (KO), and knowledge integration (KI) through knowledge formation (KF) for improving complex infrastructure project performance. Two hundred and thirty-four valid questionnaires were collected from organizations involved in complex infrastructure projects, and their responses were evaluated using partial least-squares structural equation modeling. The findings show that IS has a significant effect on the improvement of project performance and manifests as multiple mediation roles through KO, KI and KF, not via the direct effect of IS on KI and that of KO on KF. Inter-organizational trust also plays a new and positive moderating role in the relationship between KO and KI, not in the relationship between IS and KO. This study not only provides insights on the practice of knowledge management for improving complex infrastructure project performance, but it also discovers new pathways of knowledge management and relational governance through project-specific knowledge formation.