This paper argues that foreign direct investment (FDI) inflows can often lead to increases in gender disparities in more gender unequal developing countries, and that transnational corporations (TNCs) have a responsibility to supplement their normal FDI activities with additional policies and investments to ensure that women are not being made worse off. This paper begins by building a philosophical context in global gender justice, then considers empirical evidence that shows the morally problematic areas of the relationship between FDI and gender equality. It then moves on to consider why gender vulnerability to FDI needs to be addressed, drawing again on philosophical work on global gender justice. Finally, the paper uses relevant thought in cosmopolitan business ethics to establish TNCs as the responsible party for ensuring women are not being made worse off by FDI inflows and proposes a few policies and initiatives that TNCs can implement this responsibility.