We examined the relationship among supervisor–employee task conflict, supervisor ostracism, and employee depression and job performance, as well as the moderating effect of supervisors' and employees' interpersonal harmony values. Data were collected from supervisors and employees at three timewaves. We found that supervisor–employee task conflict positively predicted supervisor ostracism, which in turn predicted higher employee depression and poorer job performance. The dualistic model of interpersonal harmony proposes that people show two motives in responding to conflicts while trying to maintain interpersonal harmony: an approach motive to promote high-quality relationships (i.e. harmony enhancement) or an avoidance motive to prevent relationship disintegration (i.e. disintegration avoidance). From the supervisors' perspective, we found that supervisors' harmony enhancement values buffered the positive relationship between supervisor–employee task conflict and supervisor ostracism. From the employees' perspective, we found that employees' harmony enhancement values buffered whereas employees' disintegration avoidance value exacerbated the detrimental effect of supervisor ostracism on employee depression and job performance. Practical suggestions were offered to help both supervisors and employees manage workplace ostracism.