Considering the importance of explaining how a nation brand is effectively managed and how nation branding aligns the nation's brand with country management so as to gain competitiveness, this research aims to assess the role of nation branding and to create a strategic management tool for nation branding to achieve sustainable competitiveness of nations. Focusing on performance in nation branding, the dissertation develops a brand management model towards a systematic and strategic application for nation branding. Adopting a deductive approach based on a five-step plan for systematic research, the study proposes the Nation-Branding Mechanism Model as a mechanism-based process model. To provide empirical evidence a case study methodology is implemented involving two countries: the Republic of Korea and the Republic of Ireland. Longitudinally, the research investigates contextual variables of the nation branding process and their dynamics in branding Korea and Ireland by analyzing the "Export, Science, Technology and Industry"-brand system of Korea and the "FDI, Industry, Enterprise and Knowledge"- brand system of Ireland. The study identifies the nation-specific branding mechanisms within their nation-brand systems and the similarities and differences in both nation branding processes. An important finding is that nation branding is a process that must align with country management to influence the sustainable competitiveness of a nation and that needs a systematic approach to building a nation brand. The mechanism-based process structures a set of activities carried out by branding actors. Moreover, nation branding is an ongoing and iterative process to develop a nation-brand system and to influence a nation's sustainable competitiveness. This research suggests the ‘Nation-Branding Mechanism Model’ as an effective model for explaining performance in nation branding. Through its development, this study contributes to building a body of knowledge concerning the role of nation branding as a strategic management tool for achieving sustainable competitiveness of nations.