This study aims to unravel the accountability mechanisms that contribute to the effectiveness of NGOs. Although many past studies have shown a significant relationship between ethical leadership style and behavior, an explanation still needs to be provided. Therefore, this study was conducted to test the direct relationship between accountability to beneficiaries and NGO effectiveness and indirect relationships through mediating variables of ethical leadership. The research was conducted using an online questionnaire on 276 NGO staff, including volunteers and social workers in Malaysia. Hypothesis testing was done using Structural Equation Modeling with AMOS software. The study shows the significant role of accountability to beneficiaries in predicting NGO effectiveness, as well as the role of ethical leadership as a mediation mechanism. This study suggests that NGOs embrace the characteristics of ethical leadership in the employee training and development program.