A number of organizations have adopted coaching and mentoring interventions to discover and foster the potential capabilities of employees. These practices are seen as competitive drivers to cultivate innovation and creativity in turbulent business environments. However, the literature has not investigated the question of how coaching and mentoring are interrelated. By examining this connection, this study explores the joint effects of these practices on the organizational commitment of employees. The results from survey data of 247 employees, who were coachees as well as protégés at the same time, from 17 companies in South Korea suggested that mentoring moderates the positive relationship between managerial coaching and organizational commitment. In addition, the moderating effects also depended on the extent of the homogeneity of their coach and mentor. The positive relationship between managerial coaching and organizational commitment strongly increased with conditions of higher mentoring and lower homogeneity of coach and mentor. Conversely, the relationship became negative when both mentoring practice and the homogeneity of coach and mentor were low. These results could provide practical implications to organizations that are concurrently adopting both coaching and mentoring programs by helping managers to better understand their joint effects.