Despite a substantial literature on the consequences of leader humor, relatively few studies have examined its function of relational lubrication in a context that is full of conflict. To extend comprehension of leader humor’s broader effects, we draw on social information processing theory to investigate how and when leader humor exerts influences on team performance and team organizational citizenship behavior (OCB). We tested our model using multilevel path analysis with time-lagged, multisource data from China. Results of multilevel path analysis showed that leader humor enhanced team performance and team OCB, through prompting the development of interpersonal justice climate. These predictions were more pronounced under higher relationship conflict compared with lower relationship conflict. Taken together, our results offer new insights into the breadth of impacts of leader humor based on social information processing theory, and provide practical implications for practitioners about how to build effective teams through relational management.