Driven by increasing costs in the traditionally regarded low‐cost manufacturing bases (e.g., China), many firms have started to outsource their production to the regions of even lower costs (e.g., Southeast Asia). However, a new environment may involve higher cost uncertainty and severer information asymmetry. Motivated by these observations, we consider a sourcing game where competing firms choose between a supplier with transparent certain cost (type‐C supplier) and a supplier with potentially lower but less transparent, uncertain cost (type‐U supplier). We characterize the equilibrium of the sourcing game and study how different parameters affect the firms’ sourcing strategy and profit performance. First, we find that due to information asymmetry, a large market size can make firms prefer the C‐supplier to the U‐supplier even if the latter has a lower average cost. Second, reducing the cost uncertainty or improving the signal accuracy of the U‐supplier does not necessarily make it more attractive to sourcing firms, which cautions the suppliers when making efforts to mitigate cost uncertainty or improve cost estimation. Third, higher competition intensity makes the diversified sourcing strategy more likely to be adopted under certain conditions. Interestingly, increasing the cost of the C‐supplier (e.g., a cost hike in China) may make both sourcing firms better off because it can lead to a new sourcing equilibrium. Finally, this study shows that the direction of quantity distortion under the optimal competitive mechanism differs from that under the traditional monopolistic setting.