This study analyzes the moderating effects of the managers' characteristics and financial access barriers on the relationship between the degree of internationalization and firm performance of 131 manufacturing –and- services firms in Poland. Using the regression estimation method with panel data collected by the World Bank, we find that (1) the relationship between the degree of internationalization and firm performance has an inverted U-shape; (2) the relationship between the degree of internationalization and firm performance is positively improved when managers‟ gender is Female, in contrast, negatively decreases when firms have difficulty in accessing finance and firm managers who have more years of experience. This research's implication is the basis for policymakers and boards of directors to design appropriate corporate internationalization strategies.