Although customer aggression has been found to affect the well-being of employees in the service sector, few prior researchers have examined its effect on employees' workplace behavior. Thus, we examined the effect of customer aggression on positive and negative workplace deviant behaviors in service contexts, and explored whether psychological ownership moderates these relationships. Participants were 362 bankers in the financial sector within South Korea, and we used structural equation modeling to test the hypotheses. Results showed that customer aggression increased both destructive and constructive deviance. Further, psychological ownership moderated the relationship between customer aggression and constructive deviance, but not between customer aggression and destructive deviance. That is, customer aggression increased organizational and interpersonal constructive deviance among employees with high psychological ownership, suggesting that these employees were more likely to tackle customer aggression in an innovative manner.