Purpose Managerial effectiveness is considered as an essential element for sustainable development and competitive advantage for organisations, and its core conceptualisation revolves around the capability of management to manage self, subordinates and relationships. However, very few research addressed this important phenomenon; this study aims to fill this gap by investigating the mediating role of Islamic work ethics between leadership styles and managerial effectiveness. Design/methodology/approach Data collection was done through a structured questionnaire, and the hypothesized relationships were tested with the help of SmartPLS. Findings Results of the statistical analysis showed that transformational and transactional leadership styles are positively associated with managerial effectiveness. Also, Islamic work ethics mediated the association between transactional leadership and managerial effectiveness, and however, no mediation effect of Islamic work ethics was found in the relationship of transformational leadership and managerial effectiveness Originality/value Although volumes of research have been conducted into the nature of management and leadership over the past 50 years or so, there have been significant shortcomings in terms of little attention having been given to the issue of managerial effectiveness, lack of generalizability of findings and lack of relevance and utility; thus, this study contributed to human resource management literature by providing a macro-level model to measure managerial effectiveness.