Finance plays a critical role in the performance of investments and the overall economic development of nations. In developing countries like Nigeria, domestic savings often fall short of meeting investment needs, creating a reliance on foreign capital inflows to complement domestic resources and stimulate growth. Foreign capital can take various forms, including foreign direct investment (FDI), foreign portfolio investment (FPI), loans, and credits, each contributing differently to economic development. The volume and effectiveness of these inflows are influenced by factors such as exchange rate policies, political stability, monetary and fiscal policies, investment climate, infrastructure, and institutional quality. This study examines the role of foreign capital inflows—particularly FDI—in shaping Nigeria’s investment environment and stock market performance. By analyzing the dynamics between foreign investment and domestic capital markets, the research highlights how external financial resources can enhance liquidity, promote efficient allocation of capital, and drive sustainable economic growth. The findings underscore the importance of creating favorable macroeconomic and institutional conditions to attract and retain foreign investment for long-term development.