Parental attachment promotes moral maturity in adolescents by improving empathy. Narcissism, one of the three dark personalities, affects both empathy and moral development. However, little is known about how narcissism moderates the influence of parental attachment on moral development in adolescents. A total of 1,574 Chinese middle school students were surveyed to determine the role of narcissism and empathy in the influence of parental attachment on adolescent moral response patterns. Results showed that parental attachment significantly predicted more positive moral response patterns, with empathy serving as a mediator. Furthermore, narcissism, primarily vulnerable narcissism (versus grandiose narcissism), diminished the benefits of parental attachment to empathy, and led to a decrease in the indirect prediction of parental attachment to moral response patterns. Our findings offer empirical evidence of the negative effects of narcissism on moral development in adolescents.