People are averse to being treated unfairly, and are even willing to pay a personal cost to reject unfair others. Despite this general tendency, there might be individual differences in responses to unfairness. Across two studies, we measured participants' self-reported self-esteem and examined how people varying in self-esteem respond to unfairness in a repeated one-shot ultimatum game (Study 1, N = 160) and a one-shot ultimatum game (Study 2, N = 302). Findings revealed that participants with higher self-esteem were more likely to reject unfair offers, and that this effect was mediated by increased levels of feelings of deservingness. However, participants' self-esteem did not significantly predict their perceptions of fairness, anger, or unhappiness after receiving the unfair offers. These findings highlight the differences caused by self-esteem in acting against, but not perceiving, unfairness.