A cross-sectional study was conducted to explore the role of belief in a just world between negative life events and life satisfaction. The results revealed that two dimensions of belief in a just world played partial mediating roles between negative life events and life satisfaction. Moreover, belief in a just world was also a moderator between negative life events and life satisfaction that mitigates the adverse effects of negative life events. In conclusion, these results suggest that belief in a just world could be both a mediator and a moderator between negative life events and life satisfaction.