Prior research acknowledges employees' crucial role in building strong service brands, yet empirical research on how to turn employees into brand champions remains scarce and has been largely approached from an internal branding perspective. Drawing on social identity and social exchange theories, this study takes a broader organizational perspective to link internal branding outcomes (employee-brand fit, brand knowledge, and belief in the brand) and employees' perceptions of organizational support to a range of employee brand-building behaviors, with organizational identification as the key mediating mechanism. Both cross-sectional and longitudinal analyses of employee data from a major retail bank reveal organizational identification as a strong motivational force for employees to become brand champions, largely mediating the effects of internal branding outcomes. When organizational identification is low, perceived organizational support (as a quality indicator of employees' exchange-based relationship with the organization) constitutes an alternative, external motivator of on-the-job brand building behaviors; when organizational identification is high, perceived organizational support boosts employees' voluntary participation in brand development and positive word-of-mouth. These findings highlight the managerial relevance of the employee-organization relationship for turning employees into brand champions and show how organizational identification can be stimulated by means of internal branding.