Purpose: This study investigates the link between servant leadership and project management effectiveness in developmental projects in non-governmental organisations (NGOs). Further, this study examined the mediating role of conflict resolution and moderating role of organisational culture. Design/methodology/approach: A three-wave survey of 288 non-governmental organisation (NGO) employees was used to evaluate the hypotheses. Hierarchical regression analysis and Hayes' PROCESS macro technique were used for data analysis. Findings: In this study, servant leadership positively affects employee project management effectiveness in developmental projects in NGOs, and conflict resolution mediates the relationship. Furthermore, the results show that organisational culture moderates the positive relationship between servant leadership and employee project management effectiveness. Moreover, the authors investigated the hypotheses via a moderation mediation model. The strength of the mediated link between servant leadership and project management effectiveness (via conflict resolution) depends on organisational culture strength. Practical implications: Leaders that practice servant leadership care for their employees genuinely and serve them by allowing them to make their own decisions. Every organisation may benefit from this leadership style since it encourages project effectiveness Originality/value: New empirical data from this study suggests that servant leadership positively and substantially affects employee project management effectiveness in developmental projects in NGOs. © 2023, Emerald Publishing Limited.