Although there is a growing interest toward the topic of leader humility, extant research has largely failed to consider the underlying mechanisms through which leader humility influences team outcomes. In this research, we integrate the emerging literature of leader humility and social information processing theory to theorize how leader humility facilitates the development of collective team psychological capital, leading to higher team task allocation effectiveness and team performance. While Owens and Hekman (2016) suggest that leader humility has homogeneous effects on followers, we propose a potential heterogeneous effect based on the complementarity literature (e.g., Tiedens, Unzueta, & Young, 2007) and the principle of equifinality (leaders may influence team outcomes through multiple pathways; Morgeson, DeRue, & Karam, 2010). In three studies conducted in China, Singapore, and Portugal, including an experiment, a multisource field study, and a three-wave multisource field study, we find support for our hypotheses that leader humility enhances team performance serially through increased team psychological capital and team task allocation effectiveness. We discuss the theoretical implications of our work to the leader humility, psychological capital, and team effectiveness literatures; and offer suggestions for future research.