This meta-analysis examined the relationship between moral identity and moral behavior. It was based on 111 studies from a broad range of academic fields including business, developmental psychology and education, marketing, sociology, and sport sciences. Moral identity was found to be significantly associated with moral behavior (random effects model, r = .22, p < .01, 95% CI [.19, .25]). Effect sizes did not differ for behavioral outcomes (prosocial behavior, avoidance of antisocial behavior, ethical behavior). Studies that were entirely based on self-reports yielded larger effect sizes. In contrast, the smallest effect was found for studies that were based on implicit measures or used priming techniques to elicit moral identity. Moreover, a marginally significant effect of culture indicated that studies conducted in collectivistic cultures yielded lower effect sizes than studies from individualistic cultures. Overall, the meta-analysis provides support for the notion that moral identity strengthens individuals’ readiness to engage in prosocial and ethical behavior as well as to abstain from antisocial behavior. However, moral identity fares no better as a predictor of moral action than other psychological constructs.