This study attempts to investigate how garment suppliers upgrade themselves from one functional level to another within the global garment supply chain, and what enables them to enter into the international market. Adhering to the qualitative research approach, a comparative multiple case study method has been adopted for this study. Data were collected from three garment suppliers in Bangladesh through qualitative interviews with senior managers and thereafter utilized for developing three cases. In addition, data were collected from various secondary sources such as documents of the garment supplier factories, suppliers' websites, newspapers, and scholarly articles to corroborate the primary findings; narratives were also developed based on the collected data. Through analysis of each individual firm's case, summary findings have been derived. The study findings demonstrate that functional upgrading from cutting, making, and trimming suppliers to own brand manufacturer lays the foundation for the garment suppliers to become international brand retailers. This study also reveals that working for a long-time with different leading global garment brands, increasing production capacity gradually, enhancing design and marketing capabilities, intention to capture new market opportunities, dynamic top management and experienced managers, ability to forecast future market trends, visionary leadership, proximity to the international market(s), and political background of the owners enable suppliers to internationalize their own brands. Findings from this study would provide a lucid and useful direction to the Bangladeshi garment suppliers for their upgrading and internationalization efforts in the global market.