This paper develops a three-country, two-sector, two-factor general-equilibrium trade model in which multinational firms’ FDI decisions are influenced by global uncertainty level. We investigate the effects of economic integration under uncertainty, and highlight an important new type of FDI which is certainty-seeking. A numerical general-equilibrium model has been explored to study in depth the endogenous regime changes with six different firm types. Among others, we show that multinational firms are highly influenced by global uncertainty level, so that even the same economic integration process leads to significantly different global market structure.