Self-punishment is a highly costly—and potentially harmful—way transgressors can respond to a wrongdoing. In this research, we propose that people might punish themselves in part because it has a communicative social function. Three studies using hypothetical vignettes showed that self-punishment facilitates reconciliation with third party observers by addressing the symbolic implications of wrongdoing. Specifically, self-punishment establishes a moral value consensus and/or diminishes offender status/power, and through this, increases third party perceptions of justice and transgressor remorse, and the third party's willingness to reconcile. This effect was robust to manipulations designed to make third parties question the sincerity of the self-punisher's intention. Self-punishment thus serves a beneficial interpersonal function by repairing social bonds between transgressors and their peers.