This study aimed to analyze the association of leadership with turnover intentions and whether this relationship is mediated by employee well-being. The sample consists of approximately 306 individuals working in organizations based in Portugal. The results indicate that transformational leadership has a positive and significant association with turnover intentions, while the relationship between transactional leadership and turnover intentions is negative and significant. Both transformational leadership and transactional leadership have a positive and significant association with well-being. Well-being has a negative and significant association with turnover intentions. Well-being only has a mediating effect on the relationship between transactional leadership and turnover intentions. This study contributes to the advancement of academic research and knowledge about the mechanisms through which transformational and transactional leadership styles can influence employees’ turnover intentions, as well as providing empirical evidence on the mediating role of psychological well-being. In addition, practical insights are offered to organizational leaders and managers on adopting practices that foster psychological well-being in the workplace, thereby reducing employee turnover intentions.