Drawing on cognitive moral development and moral identity theories, this study empirically examines the moral antecedents and consequences of authentic leadership. Machiavellianism, an individual difference variable relating to the use of the ‘end justifies the means’ principle, is predicted to affect the link between morality and leadership. Analyses of multi-source, multi-method data comprised case studies, simulations, role-playing exercises, and survey questionnaires were completed by 70 managers in a large public agency, and provide support for our hypotheses. Our findings reveal that Machiavellianism offsets the positive relationship between moral reasoning and authentic leadership. Specifically, we show that when Machiavellianism is high, both the positive relationship between moral reasoning and authentic leadership, and the positive relationship between authentic leadership and moral actions, are reversed. This study offers new insights on the underlying processes contributing to the emergence of leaders’ authentic behavior and moral action. Implications for the moral development of leaders, and directions for improved leadership training are provided.