Exploitative leadership is a form of destructive leadership behavior that has adverse effects on the overall organization. This study aimed to explore the mechanisms underlying the association between exploitative leadership and employees’ unethical behavior. Drawing on ego depletion theory, we proposed a theoretical model wherein exploitative leadership increases employees’ unethical behavior through ego depletion, with microbreaks acting as a contextual condition. Using a multi-wave diary study across ten consecutive workdays from 115 employees, we found that exploitative leadership was positively associated with employees’ unethical behavior and that ego depletion mediated this relationship. Moreover, microbreaks buffer the positive relationship between exploitative leadership and ego depletion as well as the indirect effect of exploitative leadership on employees’ unethical behavior through ego depletion. We discussed the theoretical and practical implications and proposed future research directions.