This study examines the antecedents and outcomes of ethical leadership in shaping ethical culture within the Malaysian public sector. Drawing on Upper Echelons Theory, the research investigates how four leader characteristics—Machiavellianism, locus of control, ethical role modelling, and moral identity—influence ethical culture through the mediating role of ethical leadership, and whether consideration of future consequences moderates this relationship. Data were collected from 205 public service leaders across three federal ministries, and analysed using PLS-SEM. The findings reveal that ethical leadership significantly enhances ethical culture. Among the antecedents, ethical role modelling and moral identity were significant predictors of ethical leadership, whereas Machiavellianism and locus of control were not. Mediation analysis shows that ethical leadership transmits the positive effects of ethical role modelling and moral identity onto ethical culture, highlighting its central behavioural mechanism. However, ethical leadership did not mediate the impact of Machiavellianism and locus of control, as their direct relationships were nonsignificant. The moderating effect of consideration of future consequences was also not supported, indicating that ethical leadership exerts a stable influence on ethical culture regardless of employees’ future orientation. Overall, the study underscores the importance of a leader’s moral qualities and visible ethical behaviours in cultivating a strong ethical culture in public institutions.