This thesis explores the influence of MNCs on social sustainability in the RMG manufacturing industry of developing nations. While MNCs globalize their businesses worldwide, they follow the strategy of outsourcing to low-cost countries whose regimes are highly diversified. Although it brings economic benefits, there are ethical issues regarding workers' rights, working conditions, and compliance issues in supplier firms. Grounded in theoretical foundations of the Uppsala Model, the OLI paradigm, Institutional Theory, Stakeholder Theory, and the three pillars of sustainability, this study examines how MNCs, depending on their internationalization approach and CSR model, influence workplace practices in their value chain. The study followed a qualitative case study approach, and Epyllion Group, a renowned garment manufacturer, was the case. The primary data were obtained through interviews with the factory workers and management staff supported by secondary data from company sustainability reports and international labour organizations. The report acknowledges that while the global standards have prompted the changes in the shape of fire safety, documentation, and formalized grievance mechanisms, a number of issues remain unresolved. They include economic insecurity of workers, the appearance of compliance by audit trails, and lack of adequate representation or empowerment of the factory workers. The study highlights how MNCs impose coercive and normative pressures on the suppliers, providing just enough support so as to facilitate sustainable change. This research contributes to a more adequate conceptualization of the nexus between MNCs and social sustainability, emphasizing ethical obligation, equitable partnerships, and sustainable good of labour cohorts in global supply chains.