Effective stakeholder management (ESM) is a critical success factor for projects. The increasing complexity in the relationships among stakeholders and their diverse characteristics, including power and interests makes the management of stakeholders increasingly challenging. To date, much of the literature has focused on the stakeholder analysis with very limited to the direct and indirect relationships between stakeholder characteristics (SC) and project performance (PP). Therefore, the aim of this study is to fill these research gaps by empirically examining (1) the relationship(s) between SC and PP and (2) the mediation effect of ESM on the above-mentioned relationships. Data analysis was conducted using structural equation modelling. The findings suggest that stakeholder legitimate behaviour (LB), opposing behaviour (OB), and conflicting interests affect the ability to achieve both sets of quantitative and qualitative PP negatively. ESM has been identified as a key element to eliminate the negative effects of the aforementioned behaviours on qualitative (and not quantitative) PP measures.