This study examined the mediation and moderation models of the relationship between Islamic work ethics (IWE), thriving at work, organizational citizenship behavior (OCB), and leader humility. A total of 418 employees from two different sample groups (Islamic banks and educational institutions) in Indonesia were included. A multiple regression hierarchy with PROCESS was used to test the hypotheses. We found a positive influence of IWE and leader humility on thriving and OCB and thriving at work on OCB. Thriving was found to mediate the relationship between IWE and OCB, and the leader humility moderates these relationships. Thriving at work and OCB are dramatically under-represented in Islamic work ethics research, and this study attempts to fill this void. Furthermore, this study reveals the interactive role of leader humility and IWE in enhancing OCB preference and the mediating role of thriving at work in the IWE − OCB relationship.