Purpose: The purpose of this paper is to investigate the structural relationships among transformational leadership, affective organizational commitment and job performance, as well as the mediating effect of employee engagement on their relationships. Design/methodology/approach: To examine the structural relationships among the research variables, structural equation modeling analysis and bootstrap estimates were performed using the data of 600 full-time employees working in Korean private organizations. Findings: The results of the data analysis suggest that transformational leadership had a significant impact on employee affective organizational commitment and job performance through employee engagement as a mediator. Specifically, employee engagement partially mediated the mechanism in which transformational leadership affects employee affective organizational commitment, whereas there existed a full mediation of the association between transformational leadership and job performance. Practical implications: The study finding suggested that transformational leadership was the key catalyst in both encouraging affective organizational commitment and task performance of employees throughout the mediator, employee engagement. Thus, organizations need to create a safe and positive environment that promotes employee engagement and should offer interventions for leaders to build skill sets of transformational leadership. Originality/value: Because previous studies had explored the impacts of transformational leadership on employee positive attitude and job performance separately, there is little known about how these three constructs correlate. By investigating the impacts of transformational leadership on attitude and performance simultaneously in this study, this study expanded to the extant literature by providing better understanding of transformational leadership. Moreover, given that articles on transformational leadership have been limited in the HRD literature, findings of this study can offer trustworthy information for HRD practice and encourage HRD scholars to explore transformational leadership-related research.