Leader self-serving behavior has been associated with a range of adverse outcomes in the workplace. However, much remains to be explored about why and when such leader behavior emerges in organizations. This research develops and tests a theoretical framework that delineates the emotional and cognitive states that give rise to leader self-serving behavior. Specifically, we draw on uncertainty management theory to theorize that job insecurity heightens leaders' anxiety and self-serving cognitions that subsequently trigger leader self-serving behavior. We further argue that the overall justice of an organization effectively mitigates the indirect relationship between a leader's sense of job insecurity and leader self-serving behavior via leader anxiety and self-serving cognitions. Results from a three-wave field study involving 481 leader–follower dyads provide support for our hypothesized model. We discuss the implications of our findings for leadership theory and practice.