PurposeDrawing on social information processing theory and organisational identity theory, the purpose of this paper is to examine the social and psychological process through which perceived ethical leadership influences employee deviant behaviours towards the organisation. Specifically, a sequential mediation model is developed in which ethical leadership is related to employee perceptions of internal corporate social responsibility (CSR), which, in turn, are related to organisational deviance through organisational engagement.Design/methodology/approachStructural equation modeling was performed to fit the proposed model using multi-source data collected from employees and their supervisors in the Egyptian banking sector.FindingsThe results support the hypotheses, as perceived internal CSR and organisational engagement sequentially mediate the relationship between perceived ethical leadership and organisational deviance.Practical implicationsOrganisations should emphasise fostering ethical leadership through adopting strategies such as hiring ethical leaders and offering ethics training to current leaders. Organisations should also invest in internal CSR activities and should pay attention to regularly communicating their involvement in CSR initiatives to employees.Originality/valueBy examining the mediating roles of employee internal CSR perceptions and organisational engagement, this study helps advance our understanding of the social and psychological processes of ethical leadership.