Using manually collected firm-level data on foreign subsidiaries, we examine the impact of internationalization on analysts’ earnings forecast bias in Chinese corporations. We find that analysts’ earnings forecast bias is stronger among multinational firms when compared with domestic firms, and the higher the level of internationalization, the greater the bias in analysts’ earnings forecasts. Various methods, such as the Heckman two-stage least squares, propensity score matching, and difference in difference tests, are employed to ensure the robustness of our results. The mechanism analysis indicates that oversea business complexity, information asymmetry and analysts’ experience are critical factors that moderate the relationship between international diversification and forecast bias. These findings have important implications for multinational corporations, analysts, and investors.