Foreign Direct Investment (FDI) has become a critical driver of globalization and economic development in the 21st century. This study investigates the impact of FDI on multinational companies (MNCs), focusing on market expansion, financial performance, technology transfer, and global competitiveness. It explores key FDI strategies horizontal, vertical, greenfield, and brownfield and their influence on operational models. Using qualitative methods and secondary data from global sources, the report compares India and Vietnam’s FDI environments and includes a case study on Amazon to illustrate practical implications. The research highlights how FDI enables MNCs to access new markets, reduce costs, and foster innovation while also facing challenges like regulatory issues, political risks, and cultural differences. The study concludes with strategic recommendations for firms and policymakers, emphasizing local adaptation, regulatory clarity, and sustainable development as essential for maximizing FDI benefits.